cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A010815 From Euler's Pentagonal Theorem: coefficient of q^n in Product_{m>=1} (1 - q^m).

Original entry on oeis.org

1, -1, -1, 0, 0, 1, 0, 1, 0, 0, 0, 0, -1, 0, 0, -1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1
Offset: 0

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Author

Keywords

Comments

When convolved with the partition numbers A000041 gives 1, 0, 0, 0, 0, ...
Also, number of different partitions of n into parts of -1 different kinds (based upon formal analogy). - Michele Dondi (blazar(AT)lcm.mi.infn.it), Jun 29 2004
The comment that "when convolved with the partition numbers gives [1, 0, 0, 0, ...]" is equivalent to row sums of triangle A145975 = [1, 0, 0, 0, ...]; where A145975 is a partition number convolution triangle. - Gary W. Adamson, Oct 25 2008
When convolved with n-th partial sums of A000041 = the binomial sequence starting (1, n, ...). Example: A010815 convolved with A014160 (partial sum operation applied thrice to the partition numbers) = (1, 3, 6, 10, ...). - Gary W. Adamson, Nov 11 2008
(A000012^(-n) * A000041) convolved with A010815 = n-th row of the inverse of Pascal's triangle, (as a vector, followed by zeros); where A000012^(-1) = the pairwise difference operator. Example: (A000012^(-4) * A000041) convolved with A010815 = (1, -4, 6, -4, 1, 0, 0, 0, ...). - Gary W. Adamson, Nov 11 2008
Also sum of [product of (1-2/(hook lengths)^2)] over all partitions of n. - Wouter Meeussen, Sep 16 2010
Cayley (1895) begins article 387 with "Write for shortness sqrt(2k'K / pi) / [1-q^{2m-1}]^2 = G, ..." which is a convoluted way of writing G = [1-q^{2m}] = (1-q^2)(1-q^4)... - Michael Somos, Aug 01 2011
This is an example of the quintuple product identity in the form f(a*b^4, a^2/b) - (a/b) * f(a^4*b, b^2/a) = f(-a*b, -a^2*b^2) * f(-a/b, -b^2) / f(a, b) where a = x^3, b = x. - Michael Somos, Jan 21 2012
Ramanujan theta functions: f(q) (see A121373), phi(q) (A000122), psi(q) (A010054), chi(q) (A000700).
Number 1 of the 14 primitive eta-products which are holomorphic modular forms of weight 1/2 listed by D. Zagier on page 30 of "The 1-2-3 of Modular Forms". - Michael Somos, May 04 2016

Examples

			G.f. = 1 - x - x^2 + x^5 + x^7 - x^12 - x^15 + x^22 + x^26 - x^35 - x^40 + ...
G.f. = q - q^25 - q^49 + q^121 + q^169 - q^289 - q^361 + q^529 + q^625 + ...
From _Seiichi Manyama_, Mar 04 2017: (Start)
G.f.
= 1 + (-x - 3*x^2/2 - 4*x^3/3 -  7*x^4/4  -  6*x^5/5 - ...)
     + 1/2 * (x^2   + 3*x^3   + 59*x^4/12 + 15*x^5/2 + ...)
              + 1/6 * (-x^3   -  9*x^4/2  - 43*x^5/4 - ...)
                         + 1/24 * (x^4    +  6*x^5   + ...)
                                   + 1/120 * (-x^5   - ...)
                                             + ...
= 1 - x - x^2 + x^5 + .... (End)
		

References

  • M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, Tenth Printing, 1972, p. 825.
  • B. C. Berndt, Ramanujan's theory of theta-functions, Theta functions: from the classical to the modern, Amer. Math. Soc., Providence, RI, 1993, pp. 1-63. MR 94m:11054. See page 3.
  • T. J. I'a. Bromwich, Introduction to the Theory of Infinite Series, Macmillan, 2nd. ed. 1949, p. 116, Problem 18.
  • A. Cayley, An Elementary Treatise on Elliptic Functions, G. Bell and Sons, London, 1895, p. 295, Art. 387.
  • L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 104, [5g].
  • N. J. Fine, Basic Hypergeometric Series and Applications, Amer. Math. Soc., 1988; p. 77, Eq. (32.12) and (32.13).
  • G. H. Hardy, Ramanujan: twelve lectures on subjects suggested by his life and work, Cambridge, University Press, 1940, p. 86.
  • G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers, 5th ed., Oxford Univ. Press, 1979, Theorem 353.
  • B. Schoeneberg, Elliptic Modular Functions, Springer-Verlag, NY, 1974, p. 70.
  • A. Weil, Number theory: an approach through history; from Hammurapi to Legendre, Birkhäuser, Boston, 1984; see p. 186.

Crossrefs

Programs

  • Julia
    # DedekindEta is defined in A000594.
    A010815List(len) = DedekindEta(len, 1)
    A010815List(93) |> println # Peter Luschny, Mar 09 2018
    
  • Julia
    function A010815(n)
        r = 24 * n + 1
        m = isqrt(r)
        m * m != r && return 0
        iseven(div(m + m % 6, 6)) ? 1 : -1
    end # Peter Luschny, Sep 09 2021
  • Magma
    Coefficients(&*[1-x^m:m in [1..100]])[1..100] where x is PolynomialRing(Integers()).1; // Vincenzo Librandi, Jan 15 2017
    
  • Maple
    A010815 := mul((1-x^m), m=1..100);
    A010815 := proc(n) local x,m;
        product(1-x^m,m=1..n) ;
        expand(%) ;
        coeff(%,x,n) ;
    end proc: # R. J. Mathar, Jun 18 2016
    A010815 := proc(n) 24*n + 1; if issqr(%) then sqrt(%);
    (-1)^irem(iquo(% + irem(%, 6), 6), 2) else 0 fi end: # Peter Luschny, Oct 02 2022
  • Mathematica
    a[ n_] := SeriesCoefficient[ Product[ 1 - x^k, {k, n}], {x, 0, n}]; (* Michael Somos, Nov 15 2011 *)
    a[ n_] := If[ n < 0, 0, SeriesCoefficient[ (Series[ EllipticTheta[ 3, Log[y] / (2 I), x^(3/2)], {x, 0, n + Floor@Sqrt[n]}] // Normal // TrigToExp) /. {y -> -x^(1/2)}, {x, 0, n}]]; (* Michael Somos, Nov 15 2011 *)
    CoefficientList[ Series[ Product[(1 - x^k), {k, 1, 70}], {x, 0, 70}], x]
    (* hooklength[ ] cfr A047874 *) Table[ Tr[ ( Times@@(1-2/Flatten[hooklength[ # ]]^2) )&/@ Partitions[n] ],{n,26}] (* Wouter Meeussen, Sep 16 2010 *)
    CoefficientList[ Series[ QPochhammer[q], {q, 0, 100}], q] (* Jean-François Alcover, Dec 04 2013 *)
    a[ n_] := With[ {m = Sqrt[24 n + 1]}, If[ IntegerQ[m], KroneckerSymbol[ 12, m], 0]]; (* Michael Somos, Jun 04 2015 *)
    nmax = 100; poly = ConstantArray[0, nmax + 1]; poly[[1]] = 1; poly[[2]] = -1; Do[Do[poly[[j + 1]] -= poly[[j - k + 1]], {j, nmax, k, -1}];, {k, 2, nmax}]; poly (* Vaclav Kotesovec, May 04 2018 *)
    Table[m = (1 + Sqrt[1 + 24*k])/6; If[IntegerQ[m], (-1)^m, 0] + If[IntegerQ[m - 1/3], (-1)^(m - 1/3), 0], {k, 0, 100}] (* Vaclav Kotesovec, Jul 09 2020 *)
  • PARI
    {a(n) = if( n<0, 0, polcoeff( eta(x + x * O(x^n)), n))}; /* Michael Somos, Jun 05 2002 */
    
  • PARI
    {a(n) = polcoeff( prod( k=1, n, 1 - x^k, 1 + x * O(x^n)), n)}; /* Michael Somos, Nov 19 2011 */
    
  • PARI
    {a(n) = if( issquare( 24*n + 1, &n), kronecker( 12, n))}; /* Michael Somos, Feb 26 2006 */
    
  • PARI
    {a(n) = if( issquare( 24*n + 1, &n), if( (n%2) && (n%3), (-1)^round( n/6 )))}; /* Michael Somos, Feb 26 2006 */
    
  • PARI
    {a(n) = my(A); if( n<0, 0, A = 1 + O(x^n); polcoeff( sum( k=1, (sqrtint( 8*n + 1)-1) \ 2, A *= x^k / (x^k - 1) + x * O(x^(n - (k^2-k)/2)), 1), n))}; /* Michael Somos, Aug 18 2006 */
    
  • PARI
    lista(nn) = {q='q+O('q^nn); Vec(eta(q))} \\ Altug Alkan, Mar 21 2018
    
  • Python
    from math import isqrt
    def A010815(n):
        m = isqrt(24*n+1)
        return 0 if m**2 != 24*n+1 else ((-1)**((m-1)//6) if m % 6 == 1 else (-1)**((m+1)//6)) # Chai Wah Wu, Sep 08 2021
    

Formula

a(n) = (-1)^m if n is of the form m(3m+-1)/2; otherwise a(n)=0. The values of n such that |a(n)|=1 are the generalized pentagonal numbers, A001318. The values of n such that a(n)=0 is A090864.
Expansion of the Dedekind eta function without the q^(1/24) factor in powers of q.
Euler transform of period 1 sequence [ -1, -1, -1, ...].
G.f.: (q; q){oo} = Product{k >= 1} (1-q^k) = Sum_{n=-oo..oo} (-1)^n*q^(n*(3n+1)/2). The first notation is a q-Pochhammer symbol.
Expansion of f(-x) := f(-x, -x^2) in powers of x. A special case of Ramanujan's general theta function; see Berndt reference. - Michael Somos, Apr 08 2003
a(n) = A067661(n) - A067659(n). - Jon Perry, Jun 17 2003
Expansion of f(x^5, x^7) - x * f(x, x^11) in powers of x where f(, ) is Ramanujan's general theta function. - Michael Somos, Jan 21 2012
G.f.: q^(-1/24) * eta(t), where q = exp(2 Pi i t) and eta is the Dedekind eta function.
G.f.: 1 - x - x^2(1-x) - x^3(1-x)(1-x^2) - ... - Jon Perry, Aug 07 2004
Given g.f. A(x), then B(q) = q * A(q^3)^8 satisfies 0 = f(B(q), B(q^2), B(q^4)) where f(u, v, w) = u^2*w - v^3 + 16*u*w^2. - Michael Somos, May 02 2005
Given g.f. A(x), then B(q) = q * A(q^24) satisfies 0 = f(B(q), B(x^q), B(q^3), B(q^6)) where f(u1, u2, u3, u6) = u1^9*u3*u6^3 - u2^9*u3^4 + 9*u1^4*u2*u6^8. - Michael Somos, May 02 2005
a(n) = b(24*n + 1) where b() is multiplicative with b(p^2e) = (-1)^e if p == 5 or 7 (mod 12), b(p^2e) = +1 if p == 1 or 11 (mod 12) and b(p^(2e-1)) = b(2^e) = b(3^e) = 0 if e>0. - Michael Somos, May 08 2005
Given g.f. A(x), then B(q) = q * A(q^24) satisfies 0 = f(B(q), B(q^2), B(q^4)) where f(u, v, w) = u^16*w^8 - v^24 + 16*u^8*w^16. - Michael Somos, May 08 2005
a(n) = (-1)^n * A121373(n). a(25*n + 1) = -a(n). a(5*n + 3) = a(5*n + 4) = 0. a(5*n) = A113681(n). a(5*n + 2) = - A116915(n). - Michael Somos, Feb 26 2006
G.f.: 1 + Sum_{k>0} (-1)^k * x^((k^2 + k) / 2) / ((1 - x) * (1 - x^2) * ... * (1 - x^k)). - Michael Somos, Aug 18 2006
a(n) = -(1/n)*Sum_{k=1..n} sigma(k)*a(n-k). - Vladeta Jovovic, Aug 28 2002
G.f.: A(x) = 1 - x/G(0); G(k) = 1 + x - x^(k+1) - x*(1-x^(k+1))/G(k+1); (continued fraction). - Sergei N. Gladkovskii, Jan 25 2012
Expansion of f(-x^2) * chi(-x) = psi(-x) * chi(-x^2) = psi(x) * chi(-x)^2 = f(-x^2)^2 / psi(x) = phi(-x) / chi(-x) = phi(-x^2) / chi(x) in powers of x where phi(), psi(), chi(), f() are Ramanujan theta functions. - Michael Somos, Nov 16 2015
G.f.: exp( Sum_{n>=1} -sigma(n)*x^n/n ). - Seiichi Manyama, Mar 04 2017
G.f.: Sum_{n >= 0} x^(n*(2*n-1))*(2*x^(2*n) - 1)/Product_{k = 1..2*n} 1 - x^k. - Peter Bala, Feb 02 2021
The g.f. A(x) satisfies A(x^2) = Sum_{n >= 0} x^(n*(n+1)/2) * Product_{k >= n+1} 1 - x^k = 1 - x^2 - x^4 + x^10 + x^14 - x^24 - x^30 + + - - .... - Peter Bala, Feb 12 2021
For m >= 0, A(x) = (1 - x)*(1 - x^2)*...*(1 - x^m) * Sum_{n >= 0} (-1)^n * x^(n*(n+2*m+1)/2) /(Product_{k = 1..n} 1 - x^k). - Peter Bala, Feb 03 2025
From Friedjof Tellkamp, Mar 19 2025: (Start)
Sum_{n>=1} a(n)/n = 6 - 4*Pi/sqrt(3).
Sum_{n>=1} a(n)/n^2 = -108 + 16*sqrt(3)*Pi + 2*Pi^2.
Sum_{n>=1} a(n)/n^k = Sum_{i=0..k} 6^(k-i)*C(-k, k-i)*A(i), where A(i)=(2^i-2)*(3^i-3)*zeta(i) for even i, and A(i)=-G(i/2-1/2)*(2^i+2)*(2*Pi)^i/(sqrt(3)*Gamma(i+1)) for odd i, with G(n>0) as the Glaisher's numbers (A002111) and G(0)=1/2. (End)

Extensions

Additional comments from Michael Somos, Jun 05 2002

A001453 Catalan numbers - 1.

Original entry on oeis.org

1, 4, 13, 41, 131, 428, 1429, 4861, 16795, 58785, 208011, 742899, 2674439, 9694844, 35357669, 129644789, 477638699, 1767263189, 6564120419, 24466267019, 91482563639, 343059613649, 1289904147323, 4861946401451, 18367353072151, 69533550916003, 263747951750359
Offset: 2

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Author

Keywords

References

  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A000108, A001454. Column k=2 of A047874.
A141364 is essentially the same sequence.
All of A000108, A001453, A246604, A273526, A120304, A289615, A289616, A289652, A289653, A289654 are very similar sequences.

Programs

Formula

a(n) = A000108(n) - 1 = binomial(2*n,n)/(n+1) - 1.
D-finite with recurrence: (n+1)*a(n) +2*(-3*n+1)*a(n-1) +(9*n-13)*a(n-2) +2*(-2*n+5)*a(n-3)=0. - R. J. Mathar, Sep 04 2013
a(n) = Sum_{k=1..floor(n/2)} (C(n,k)-C(n,k-1))^2. - J. M. Bergot, Sep 17 2013
a(n) = Sum_{k=1..n-1} A000245(n-k-1). - John M. Campbell, Dec 28 2016
From Ilya Gutkovskiy, Dec 28 2016: (Start)
O.g.f.: (1 - sqrt(1 - 4*x))/(2*x) - 1/(1 - x).
E.g.f.: exp(x)*(exp(x)*(BesselI(0,2*x) - BesselI(1,2*x)) - 1). (End)
a(n)= 3*Sum_{k=1..n} binomial(2*k-2,k)/(k+1). - Gary Detlefs, Feb 14 2020

Extensions

More terms from James Sellers, Sep 08 2000

A245667 Number T(n,k) of sequences in {1,...,n}^n with longest increasing subsequence of length k; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 0, 1, 0, 3, 1, 0, 10, 16, 1, 0, 35, 175, 45, 1, 0, 126, 1771, 1131, 96, 1, 0, 462, 17906, 23611, 4501, 175, 1, 0, 1716, 184920, 461154, 161876, 13588, 288, 1, 0, 6435, 1958979, 8837823, 5179791, 759501, 34245, 441, 1, 0, 24310, 21253375, 169844455, 157279903, 36156355, 2785525, 75925, 640, 1
Offset: 0

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Author

Alois P. Heinz, Jul 28 2014

Keywords

Comments

Sum_{k=0..1} T(n,k) = A088218(n).
Sum_{k=0..2} T(n,k) = A239295(n).
Sum_{k=0..3} T(n,k) = A239299(n).
Sum_{k=1..n} k * T(n,k) = A275576(n).

Examples

			T(3,1) = 10: [1,1,1], [2,1,1], [2,2,1], [2,2,2], [3,1,1], [3,2,1], [3,2,2], [3,3,1], [3,3,2], [3,3,3].
T(3,3) = 1: [1,2,3].
Triangle T(n,k) begins:
  1;
  0,    1;
  0,    3,      1;
  0,   10,     16,      1;
  0,   35,    175,     45,      1;
  0,  126,   1771,   1131,     96,     1;
  0,  462,  17906,  23611,   4501,   175,   1;
  0, 1716, 184920, 461154, 161876, 13588, 288,  1;
  ...
		

Crossrefs

Columns k=0-10 give: A000007, A088218 or A001700(n-1) for n>0, A268869, A268870, A268871, A268872, A268873, A268874, A268875, A268876, A268877.
Main diagonal gives A000012.
T(n,n-1) gives A152618(n) for n>0.
T(n,n-2) gives A268936(n).
T(2n,n) gives A268949(n).
Row sums give A000312.

Programs

  • Maple
    b:= proc(n, l) option remember; `if`(n=0, 1, add(b(n-1, [seq(min(l[j],
          `if`(j=1 or l[j-1] `if`(k=0, `if`(n=0, 1, 0), b(n, [n$k])):
    T:= (n, k)-> A(n, k) -`if`(k=0, 0, A(n, k-1)):
    seq(seq(T(n, k), k=0..n), n=0..9);
  • Mathematica
    b[n_, l_List] := b[n, l] = If[n == 0, 1, Sum[b[n-1, Table[Min[l[[j]], If[j == 1 || l[[j-1]]Jean-François Alcover, Feb 04 2015, after Alois P. Heinz *)

A003316 Sum of lengths of longest increasing subsequences of all permutations of n elements.

Original entry on oeis.org

1, 3, 12, 58, 335, 2261, 17465, 152020, 1473057, 15730705, 183571817, 2324298010, 31737207034, 464904410985, 7272666016725, 121007866402968, 2133917906948645, 39756493513248129, 780313261631908137, 16093326774432620874, 347958942706716524974
Offset: 1

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Author

Keywords

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A008304 (which is concerned with runs of adjacent elements).
Row sums of A214152.

Programs

  • Maple
    h:= proc(l) local n; n:= nops(l); add(i, i=l)! /mul(mul(1+l[i]-j+
          add(`if`(l[k]>=j, 1, 0), k=i+1..n), j=1..l[i]), i=1..n) end:
    g:= (n, i, l)-> `if`(n=0 or i=1, h([l[], 1$n])^2, `if`(i<1, 0,
                    add(g(n-i*j, i-1, [l[], i$j]), j=0..n/i))):
    a:= n-> add(k* (g(n-k, k, [k])), k=1..n):
    seq(a(n), n=1..22);  # Alois P. Heinz, Jul 05 2012
  • Mathematica
    h[l_List] := Module[{n = Length[l]}, Total[l]!/Product[Product[1+l[[i]]-j+Sum[If[l[[k]] >= j, 1, 0], {k, i+1, n}], {j, 1, l[[i]]}], {i, 1, n}]]; g[n_, i_, l_] := If[n == 0 || i == 1, h[Join[l, Array[1&, n]]]^2, If[i<1, 0, Sum[g[n-i*j, i-1, Join[l, Array[i&, j]]], {j, 0, n/i}]]]; a[n_] := Sum[k*g[n-k, k, {k}], {k, 1, n}]; Table[a[n], {n, 1, 22}] (* Jean-François Alcover, Feb 11 2014, after Alois P. Heinz *)

Formula

From Alois P. Heinz, Nov 04 2018: (Start)
a(n) = Sum_{k=1..n} k * A047874(n,k).
A321274(n) < a(n) < A321273(n) for n > 1. (End)
A theorem of Vershik and Kerov (1977) implies that a(n) ~ 2 * sqrt(n) * n!. - Ludovic Schwob, Apr 04 2024

Extensions

Corrected a(13) and extended beyond a(16) by Alois P. Heinz, Jul 05 2012

A214152 Number of permutations T(n,k) in S_n containing an increasing subsequence of length k; triangle T(n,k), n>=1, 1<=k<=n, read by rows.

Original entry on oeis.org

1, 2, 1, 6, 5, 1, 24, 23, 10, 1, 120, 119, 78, 17, 1, 720, 719, 588, 207, 26, 1, 5040, 5039, 4611, 2279, 458, 37, 1, 40320, 40319, 38890, 24553, 6996, 891, 50, 1, 362880, 362879, 358018, 268521, 101072, 18043, 1578, 65, 1, 3628800, 3628799, 3612004, 3042210, 1438112, 337210, 40884, 2603, 82, 1
Offset: 1

Views

Author

Alois P. Heinz, Jul 05 2012

Keywords

Examples

			T(3,2) = 5.  All 3! = 6 permutations of {1,2,3} contain an increasing subsequence of length 2 with the exception of 321.
Triangle T(n,k) begins:
     1;
     2,    1;
     6,    5,    1;
    24,   23,   10,    1;
   120,  119,   78,   17,   1;
   720,  719,  588,  207,  26,  1;
  5040, 5039, 4611, 2279, 458, 37,  1;
  ...
		

Crossrefs

Columns k=1-10 give: A000142 (for n>0), A033312, A056986, A158005, A158432, A159139, A159175, A217675, A217676, A217677.
Row sums give: A003316.
T(2n,n) gives A269021.
Diagonal and lower diagonals give: A000012, A002522, A217200, A217193.

Programs

  • Maple
    h:= proc(l) local n; n:=nops(l); add(i, i=l)! /mul(mul(1+l[i]-j
          +add(`if`(l[k]>=j, 1, 0), k=i+1..n), j=1..l[i]), i=1..n)
        end:
    g:= (n, i, l)-> `if`(n=0 or i=1, h([l[], 1$n])^2, `if`(i<1, 0,
                     add(g(n-i*j, i-1, [l[], i$j]), j=0..n/i))):
    T:= (n, k)-> n! -g(n, k-1, []):
    seq(seq(T(n, k), k=1..n), n=1..12);
  • Mathematica
    h[l_] := With[{n = Length[l]}, Sum[i, {i, l}]! / Product[Product[1 + l[[i]] - j + Sum[If[l[[k]] >= j, 1, 0], {k, i+1, n}], {j, 1, l[[i]]}], {i, 1, n}] ]; g[n_, i_, l_] := If[n == 0 || i === 1, h[Join[l, Array[1&, n]]]^2, If[i < 1, 0, Sum[g[n - i*j, i-1, Join[l, Array[i&, j]]], {j, 0, n/i}]]]; t[n_, k_] := n! - g[n, k-1, {}]; Table[Table[t[n, k], {k, 1, n}], {n, 1, 12}] // Flatten (* Jean-François Alcover, Dec 17 2013, translated from Maple *)

Formula

T(n,k) = Sum_{i=k..n} A047874(n,i).
T(n,k) = A000142(n) - A214015(n,k-1).

A047888 Rectangular array of numbers a(n,k) = number of permutations of n things with longest increasing subsequence of length <= k (1 <= k <= oo), read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 5, 2, 1, 1, 14, 6, 2, 1, 1, 42, 23, 6, 2, 1, 1, 132, 103, 24, 6, 2, 1, 1, 429, 513, 119, 24, 6, 2, 1, 1, 1430, 2761, 694, 120, 24, 6, 2, 1, 1, 4862, 15767, 4582, 719, 120, 24, 6, 2, 1, 1, 16796, 94359, 33324, 5003, 720, 120, 24, 6, 2, 1, 1, 58786, 586590
Offset: 1

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Author

Eric Rains (rains(AT)caltech.edu), N. J. A. Sloane

Keywords

Comments

Also a(n,k) is the dimension of the space of SL(k)-invariants in V^n tensor (V^*)^n, where V is the standard k-dimensional representation of SL(k) and V^* is its dual. - Alec Mihailovs (alec(AT)mihailovs.com), Aug 14 2005

Examples

			Square array a(n,k) begins:
  1,   1,    1,    1,    1,    1, ...
  1,   2,    2,    2,    2,    2, ...
  1,   5,    6,    6,    6,    6, ...
  1,  14,   23,   24,   24,   24, ...
  1,  42,  103,  119,  120,  120, ...
  1, 132,  513,  694,  719,  720, ...
		

Crossrefs

Rows of the array are partial sums of A047874. Cf. A047887.
Subarray of A214015.

Programs

  • Mathematica
    rows = 12; h[l_List] := Module[{n = Length[l]}, Total[l]!/Product[Product[1+l[[i]]-j+Sum[If[l[[k]] >= j, 1, 0], {k, i+1, n}], {j, 1, l[[i]]}], {i, 1, n}]] ; g[n_, i_, l_List] := If[n == 0 || i == 1, h[Join[l, Array[1&, n]]]^2, If[i<1, 0, Sum[g[n-i*j, i-1, Join[l, Array[i&, j]]], {j, 0, n/i}]]]; T[n_] := Table[g[n-k, Min[n-k, k], {k}], {k, 1, rows}] // Accumulate; A047888 = Table[T[n], {n, 1, rows}]; Table[A047888[[n-k+1, k]], {n, 1, rows}, {k, 1, n}] // Flatten (* Jean-François Alcover, Mar 06 2014, after Alois P. Heinz *)
  • PARI
    b(n, k) = {
      my(x = 'x + O('x^(2*n)));
      sum(i = 0, n, x^(2*i+k)/(i!*(i+k)!));
    };
    u(n, k) = {
      my(v = Vec(matdet(matrix(k, k, i, j, b(n, abs(i-j))))));
      return(vector((#v-1)\2, i, v[2*i+1] * i!^2));
    };
    A(n, k) = {
      my(m = [;]);
      for (i = 1, k, m = concat(m, u(n, i)~));
      return(m);
    };
    A(6, 6)  \\ Gheorghe Coserea, Feb 02 2016

Extensions

More terms from Naohiro Nomoto, Mar 01 2002

A001454 Number of permutations of length n with longest increasing subsequence of length 3.

Original entry on oeis.org

1, 9, 61, 381, 2332, 14337, 89497, 569794, 3704504, 24584693, 166335677, 1145533650, 8017098273, 56928364553, 409558170361, 2981386305018, 21935294881644, 162951791097669, 1221201051018189, 9225637750090023, 70209505971502533, 537934326588404973
Offset: 3

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Author

Keywords

References

  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A001453. Column k=3 of A047874.

Programs

  • Maple
    a:= proc(n) option remember; `if`(n<3, 0, `if`(n=3, 1,
          (18*(n-1)*(2*n-5)*(3*n^2+2*n-3)*(n-2)^2*a(n-3)
          -(n-1)*(147*n^5-553*n^4+199*n^3+937*n^2-790*n+96)*a(n-2)
          +(n+1)*(42*n^5-146*n^4+21*n^3+171*n^2+14*n-48)*a(n-1))/
           ((n-3)*(n+1)*(3*n^2-4*n-2)*(n+2)^2)))
        end:
    seq(a(n), n=3..30);  # Alois P. Heinz, Sep 28 2012
  • Mathematica
    h[l_List] := Module[{n = Length[l]}, Total[l]!/Product[Product[1+l[[i]]-j+Sum[If[l[[k]] >= j, 1, 0], {k, i+1, n}], {j, 1, l[[i]]}], {i, 1, n}]]; g[n_, i_, l_List] := If[n == 0 || i == 1, h[Join[l, Array[1&, n]]]^2, If[i<1, 0, Sum[g[n-i*j, i-1, Join[l, Array[i&, j]]], {j, 0, n/i}]]]; T[n_] := Table[g[n-k, Min[n-k, k], {k}], {k, 1, n}]; Table[T[n], {n, 3, 24}][[All, 3]] (* Jean-François Alcover, Mar 11 2014, after Alois P. Heinz *)

Formula

a(n) ~ 3^(2*n + 4 + 1/2)/(16*Pi*n^4). - Vaclav Kotesovec, Aug 16 2013

Extensions

More terms from Pab Ter (pabrlos2(AT)hotmail.com), Oct 17 2005

A047887 Triangle of numbers T(n,k) = number of permutations of n things with longest increasing subsequence of length <=k (1<=k<=n).

Original entry on oeis.org

1, 1, 2, 1, 5, 6, 1, 14, 23, 24, 1, 42, 103, 119, 120, 1, 132, 513, 694, 719, 720, 1, 429, 2761, 4582, 5003, 5039, 5040, 1, 1430, 15767, 33324, 39429, 40270, 40319, 40320, 1, 4862, 94359, 261808, 344837, 361302, 362815, 362879, 362880, 1, 16796
Offset: 1

Views

Author

Eric Rains (rains(AT)caltech.edu), N. J. A. Sloane

Keywords

Examples

			Triangle T(n,k) begins:
  1;
  1,   2;
  1,   5,    6;
  1,  14,   23,   24;
  1,  42,  103,  119,  120;
  1, 132,  513,  694,  719,  720;
  1, 429, 2761, 4582, 5003, 5039, 5040;
  ...
		

Crossrefs

Rows are partial sums of A047874.

Programs

  • Mathematica
    h[l_] := Module[{n = Length[l]}, Total[l]!/Product[Product[1 + l[[i]] - j + Sum[If[l[[k]] >= j, 1, 0], {k, i + 1, n}], {j, 1, l[[i]]}], {i, 1, n}]];
    g[n_, i_, l_] := If[n == 0 || i == 1, h[Join[l, Array[1 &, n]]]^2, If[i < 1, 0, Sum[g[n - i*j, i - 1, Join[l, Array[i &, j]]], {j, 0, n/i}]]];
    T[n_] := Table[g[n - k, Min[n - k, k], {k}], {k, 1, n}] // Accumulate;
    Table[T[n], {n, 1, 10}] // Flatten (* Jean-François Alcover, Mar 24 2016, after Alois P. Heinz *)

Extensions

More terms from Naohiro Nomoto, Mar 01 2002

A267433 Number of permutations of [2n] with longest increasing subsequence of length n.

Original entry on oeis.org

1, 1, 13, 381, 17557, 1100902, 87116283, 8312317976, 927716186325, 118504614869214, 17044414451764396, 2725298085020712539, 479491040778079234419, 92050364310704637832186, 19146538134094625864605786, 4289203871330156652985437480
Offset: 0

Views

Author

Alois P. Heinz, Jan 15 2016

Keywords

Examples

			a(2) = 13: 1432, 2143, 2413, 2431, 3142, 3214, 3241, 3412, 3421, 4132, 4213, 4231, 4312.
		

Crossrefs

Programs

  • Maple
    h:= proc(l) local n; n:= nops(l); add(i, i=l)! /mul(mul(1+l[i]-j+
        add(`if`(l[k]>=j, 1, 0), k=i+1..n), j=1..l[i]), i=1..n) end:
    g:= (n, i, l)-> `if`(n=0 or i=1, h([l[], 1$n])^2, `if`(i<1, 0,
                    add(g(n-i*j, i-1, [l[], i$j]), j=0..n/i))):
    a:= n-> g(n$2, [n]):
    seq(a(n), n=0..20);
  • Mathematica
    h[l_] := With[{n = Length[l]}, Total[l]! / Product[Product[1 + l[[i]] - j + Sum[If[l[[k]] >= j, 1, 0], { k, i+1, n}], {j, 1, l[[i]]}], {i, 1, n}]];
    g[n_, i_, l_] := g[n, i, l] = If[n==0 || i==1, h[Join[l, Table[1, {n}]]]^2, If[i<1, 0, Sum[g[n-i*j, i-1, Join[l, Table[i, {j}]]], {j, 0, n/i}]]];
    a[n_] := g[n, n, {n}];
    Table[a[n], {n, 0, 20}] (* Jean-François Alcover, Mar 29 2017, translated from Maple *)

Formula

a(n) = A047874(2n,n) = A126065(2n,n).
a(n) ~ 16^n * (n-1)! / (Pi * exp(2)). - Vaclav Kotesovec, Mar 27 2016

A224652 Triangle read by rows: T(n,k) is the number of permutations of n elements with k the (smallest) header (first element) of the longest descending subsequence.

Original entry on oeis.org

1, 1, 1, 1, 2, 3, 1, 5, 8, 10, 1, 14, 25, 35, 45, 1, 42, 89, 141, 196, 251, 1, 132, 357, 644, 966, 1302, 1638, 1, 429, 1602, 3284, 5300, 7526, 9878, 12300, 1, 1430, 7959, 18423, 31947, 47859, 65619, 84765, 104877, 1, 4862, 43127, 112255, 209500, 331795, 475738, 637657, 813730, 1000135
Offset: 1

Views

Author

Joerg Arndt, Apr 13 2013

Keywords

Comments

Table II "Distribution of F_n" on p. 99 of the Pilpel reference.
Column 2 is A000108; column 3 is A006219; the diagonal is A006220; the row sums are A000142.

Examples

			Triangle begins
1;
1, 1;
1, 2, 3;
1, 5, 8, 10;
1, 14, 25, 35, 45;
1, 42, 89, 141, 196, 251;
1, 132, 357, 644, 966, 1302, 1638;
1, 429, 1602, 3284, 5300, 7526, 9878, 12300;
1, 1430, 7959, 18423, 31947, 47859, 65619, 84765, 104877;
1, 4862, 43127, 112255, 209500, 331795, 475738, 637657, 813730, 1000135;
...
		

Crossrefs

Cf. A000108, A006219, A006220, A000142 (row sums).
Cf. A047874 (Table I, "Distribution of L_n" on p. 99 of the Pilpel reference).
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