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.

Showing 1-7 of 7 results.

A053657 a(n) = Product_{p prime} p^{ Sum_{k>=0} floor[(n-1)/((p-1)p^k)]}.

Original entry on oeis.org

1, 2, 24, 48, 5760, 11520, 2903040, 5806080, 1393459200, 2786918400, 367873228800, 735746457600, 24103053950976000, 48206107901952000, 578473294823424000, 1156946589646848000, 9440684171518279680000, 18881368343036559360000, 271211974879377138647040000
Offset: 1

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Author

Jean-Luc Chabert, Feb 16 2000

Keywords

Comments

LCM of denominators of the coefficients of x^n*z^k in {-log(1-x)/x}^z as k=0..n, as described by triangle A075264.
Denominators of integer-valued polynomials on prime numbers (with degree n): 1/a(n) is a generator of the ideal formed by the leading coefficients of integer-valued polynomials on prime numbers with degree less than or equal to n.
Also the least common multiple of the orders of all finite subgroups of GL_n(Q) [Minkowski]. Schur's notation for the sequence is M_n = a(n+1). - Martin Lorenz (lorenz(AT)math.temple.edu), May 18 2005
This sequence also occurs in algebraic topology where it gives the denominators of the Laurent polynomials forming a regular basis for K*K, the hopf algebroid of stable cooperations for complex K-theory. Several different equivalent formulas for the terms of the sequence occur in the literature. An early reference is K. Johnson, Illinois J. Math. 28(1), 1984, pp.57-63 where it occurs in lines 1-5, page 58. A summary of some of the other formulas is given in the appendix to K. Johnson, Jour. of K-theory 2(1), 2008, 123-145. - Keith Johnson (johnson(AT)mscs.dal.ca), Nov 03 2008
a(n) is divisible by n!, by Legendre's formula for the highest power of a prime that divides n!. Also, a(n) is divisible by (n+1)! if and only if n+1 is not prime. - Jonathan Sondow, Jul 23 2009
Triangle A163940 is related to the divergent series 1^m*1! - 2^m*2! + 3^m*3! - 4^m*4! + ... for m =>-1. The left hand columns of this triangle can be generated with the MC polynomials, see A163972. The Minkowski numbers appear in the denominators of these polynomials. - Johannes W. Meijer, Oct 16 2009
Unsigned Stirling numbers of the first kind as [s + k, k] (Karamata's notation) where k = {0, 1, 2, ...} and s is in general complex results in Pochhammer[s,k]*(integer coefficient polynomial of (k-1) degree in s) / M[k], where M[k] is the least common multiple of the orders of all finite groups of n x n-matrices over rational numbers (Minkowiski's theorem) which is sequence A053657. - Lorenz H. Menke, Jr., Feb 02 2010
From Peter Bala, Feb 21 2011: (Start)
Given a subset S of the integers Z, Bhargava has shown how to associate with S a generalized factorial function, denoted n!_S, which shares many properties of the classical factorial function n!.
The present sequence is the generalized factorial function n!S associated with the set of primes S = {2,3,5,7,...}. The associated generalized exponential function E(x) = Sum{n>=1} x^(n-1)/a(n) vanishes at x = -2: i.e. Sum_{n>=1} (-2)^n/a(n) = 0.
For the table of associated generalized binomial coefficients n!_S/(k!_S*(n-k)!_S) see A186430.
This sequence is related to the Bernoulli polynomials in two ways [Chabert and Cahen]:
(1) a(n) = (n-1)!*A001898(n-1).
(2) (t/(exp(t)-1))^x = sum {n = 0..inf} P(n,x)*t^n/a(n+1),
where the P(n,x) are primitive polynomials in the ring Z[x].
If p_1,...,p_n are any n primes then the product of their pairwise differences Product_{i
(End)
LCM of denominators of the coefficients of S(m+n-1,m) as polynomial in m of degree 2*(n-1), as described by triangle A202339. - Vladimir Shevelev, Dec 17 2011
Sometimes called "Minkowski numbers" (e.g., by Guralnick and Lorenz), after the German mathematician Hermann Minkowski (1864-1909). - Amiram Eldar, Aug 24 2024

Examples

			a(7)=24^3*Product_{i=1..3} A202318(i)=24^3*1*10*21=2903040. - _Vladimir Shevelev_, Dec 17 2011
		

References

  • Jean-Luc Chabert, Scott T. Chapman, and William W. Smith, A basis for the ring of polynomials integer-valued on prime numbers, in: Daniel Anderson (ed.), Factorization in integral domains, Lecture Notes in Pure and Appl. Math. 189, Dekker, New York, 1997.

Crossrefs

a(n) = n!*A163176(n). - Jonathan Sondow, Jul 23 2009
Cf. A202318.
Appears in A163972. - Johannes W. Meijer, Oct 16 2009

Programs

  • Maple
    A053657 := proc(n) local P,p,q,s,r;
    P := select(isprime,[$2..n]); r:=1;
    for p in P do s := 0; q := p-1;
    do if q > (n-1) then break fi;
    s := s + iquo(n-1,q); q := q*p; od;
    r := r * p^s; od; r end: # Peter Luschny, Jul 26 2009
    ser := series((y/(exp(y)-1))^x, y, 20): a := n -> denom(coeff(ser, y, n-1)):
    seq(a(n), n=1..19); # Peter Luschny, May 13 2019
  • Mathematica
    m = 16; s = Expand[Normal[Series[(-Log[1-x]/x)^z, {x, 0, m}]]];
    a[n_, k_] := Denominator[ Coefficient[s, x^n*z^k]];
    Prepend[Apply[LCM, Table[a[n,k], {n,m}, {k,n}], {1}], 1]
    (* Jean-François Alcover, May 31 2011 *)
    a[n_] := Product[p^Sum[Floor[(n-1)/((p-1) p^k)], {k, 0, n}], {p, Prime[ Range[n] ]}]; Array[a, 30] (* Jean-François Alcover, Nov 22 2016 *)
  • PARI
    {a(n)=local(X=x+x^2*O(x^n),D);D=1;for(j=0,n-1,D=lcm(D,denominator( polcoeff(polcoeff((-log(1-X)/x)^z+z*O(z^j),j,z),n-1,x))));return(D)} /* Paul D. Hanna, Jun 27 2005 */
    
  • PARI
    {a(n)=prod(i=1,#factor(n!)~,prime(i)^sum(k=0,#binary(n), floor((n-1)/((prime(i)-1)*prime(i)^k))))} /* Paul D. Hanna, Jun 27 2005 */
    
  • PARI
    S(n, p) = {
         my(acc = 0, tmp = p-1);
         while (tmp < n, acc += floor((n-1)/tmp); tmp *= p);
         return(acc);
    };
    a(n) = {
         my(rv = 1);
         forprime(p = 2, n, rv *= p^S(n,p));
         return(rv);
    };
    vector(17, i, a(i))  \\ Gheorghe Coserea, Aug 24 2015

Formula

a(2n) = 2*a(2n-1). - Jonathan Sondow, Jul 23 2009
a(2*n+1) = 24^n * Product_{i=1..n} A202318(i). - Vladimir Shevelev, Dec 17 2011
For n>=0, A007814(a(n+1)) = n+A007814(n!). - Vladimir Shevelev, Dec 28 2011
a(n) = denominator([y^(n-1)] (y/(exp(y)-1))^x). - Peter Luschny, May 13 2019
Sum_{n>=1} 1/a(n) = A346046. - Amiram Eldar, Jul 02 2023

Extensions

More terms from Paul D. Hanna, Jun 27 2005

A075266 Numerator of the coefficient of x^n in log(-log(1-x)/x).

Original entry on oeis.org

0, 1, 5, 1, 251, 19, 19087, 751, 1070017, 2857, 26842253, 434293, 703604254357, 8181904909, 1166309819657, 5044289, 8092989203533249, 5026792806787, 12600467236042756559, 69028763155644023, 8136836498467582599787
Offset: 0

Author

Paul D. Hanna, Sep 15 2002

Keywords

Comments

A series with these numerators leads to Euler's constant: gamma = 1 - 1/4 - 5/72 - 1/32 - 251/14400 - 19/1728 - 19087/2540160 - ..., see references [Blagouchine] below, as well as A262235. - Iaroslav V. Blagouchine, Sep 15 2015

Crossrefs

Cf. A053657, A075264, A075267 (denominator), A262235.

Programs

  • Maple
    S:= series(log(-log(1-x)/x),x,51):
    seq(numer(coeff(S,x,j)),j=0..50); # Robert Israel, May 17 2016
    # Alternative:
    a := proc(n) local r; r := proc(n) option remember; if n=0 then 1 else
    1 - add(r(k)/(n-k+1), k=0..n-1) fi end: numer(r(n)/(n*(n+1))) end:
    seq(a(n), n=0..20); # Peter Luschny, Apr 19 2018
  • Mathematica
    Numerator[ CoefficientList[ Series[ Log[ -Log[1 - x]/x], {x, 0, 20}], x]]
  • SageMath
    @cached_function
    def r(n): return 1 - sum(r(k)/(n-k+1) for k in range(n)) if n > 0 else 1
    def a(n: int): return numerator(r(n)/(n*(n+1))) if n > 0 else 0
    print([a(n) for n in range(21)])  # Peter Luschny, Aug 15 2025

Formula

a(n) = numerator(Sum_{k=1..n} (k-1)!*(-1)^(n-k-1)*binomial(n,k)*Stirling1(n+k,k)/(n+k)!). - Vladimir Kruchinin, Aug 14 2025

Extensions

Edited by Robert G. Wilson v, Sep 17 2002
a(0) = 0 prepended by Peter Luschny, Aug 15 2025

A075267 Denominator of the coefficient of x^n in log(-log(1-x)/x).

Original entry on oeis.org

2, 24, 8, 2880, 288, 362880, 17280, 29030400, 89600, 958003200, 17418240, 31384184832000, 402361344000, 62768369664000, 295206912, 512189896458240000, 342372925440000, 919636959090769920000, 5377993912811520000, 674400436666564608000000, 89903156428800000
Offset: 1

Author

Paul D. Hanna, Sep 15 2002

Keywords

Crossrefs

Cf. A075266 (numerator), A075264, A053657.

Programs

  • Magma
    m:=25; R:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!( Log(-Log(1-x)/x) )); [Denominator(b[n]): n in [1..m-2]]; // G. C. Greubel, Oct 29 2018
  • Maple
    S:= series(log(-log(1-x)/x),x,51):
    seq(denom(coeff(S,x,j)),j=1..50); # Robert Israel, May 17 2016
  • Mathematica
    Denominator[ CoefficientList[ Series[ Log[ -Log[1 - x]/x], {x, 0, 18}], x]]

Formula

a(n) = denominator(Sum_{k=1..n} (k-1)!*(-1)^(n-k-1)*binomial(n,k)*Stirling1(n+k,k)/(n+k)!). - Vladimir Kruchinin, Aug 14 2025

Extensions

Edited by Robert G. Wilson v, Sep 17 2002

A163972 The MC polynomials.

Original entry on oeis.org

1, 0, 3, 1, 0, 2, 45, 22, 3, 0, 0, 10, 107, 61, 13, 1, 0, -48, 20, 2100, 14855, 9168, 2390, 300, 15, 0, 0, -336, 92, 6320, 33765, 21803, 6378, 1010, 85, 3, 0, 11520, -2016, -198296, 33012, 2199246, 9547461, 6331782, 1994265, 362474, 39375, 2394, 63
Offset: 1

Author

Johannes W. Meijer, Aug 13 2009

Keywords

Comments

The a(n,p) polynomials, see below with the extra p for the column number, generate the coefficients of the left hand columns of triangle A163940. These polynomials are interesting in their own right. They have many curious properties; e.g., for p >= 1: a(n=1, p) = p, a(n=0, p) = 0, a(n = -1, p) = (-1)^(p+1), a(n=-2,p) = (-1)^(p+1)*(2)^(p-2) and a(n = -(2*p+1), 2*p) = 0, which is the outermost zero of the a(n, 2*p); for p >= 10: a(n=-10, p) = -362880*10^(p-10); etc.
The numbers in the denominators of the a(n,p) are the Minkowski numbers A053657.
The Maple program generates the coefficients of the polynomials that appear in the numerators of the a(n,p), see the sequence above. We have made use of a nice little program that Peter Luschny recently wrote for the Minkowski numbers! For the an(p,k) in the Maple program for p >= 1 we have 0 <= k <= (2*p-2). A word of caution: The value of nmax has to be chosen sufficiently large in order to let Maple find the o.g.f.s.
The zero patterns of the a(n,p) polynomials resemble the Montezuma Cypress (Taxodium mucronatum). A famous Montezuma Cypress is 'El Arbol del Tule' (the Tule tree) in Mexico. It is the second stoutest tree in the world, circumference 36 meters, and is approximately 1500 years old. Considering this I propose to call the a(n,p) polynomials the MC polynomials.
The row sums equal n*A053657(n). [Johannes W. Meijer, Nov 29 2012]

Examples

			The a(n,p) formulas of the first few left hand columns of the A163940 triangle (p is the column number):
a(n,1) = (1)/1
a(n,2) = (0 + 3*n + n^2)/2
a(n,3) = (0 + 2*n + 45*n^2+ 22*n^3 + 3*n^4)/24
a(n,4) = (0 + 0*n + 10*n^2 + 107*n^3 + 61*n^4 + 13*n^5 + n^6)/48
a(n,5) = (0 - 48*n + 20*n^2 + 2100*n^3 + 14855*n^4 + 9168*n^5 + 2390*n^6 + 300*n^7 + 15*n^8)/5760
a(n,6) = (0 + 0*n -336*n^2 +92*n^3 +6320*n^4 +33765*n^5 +21803*n^6 +6378*n^7 +1010*n^8 +85*n^9 +3*n^10)/11520
a(n,7) = (0 + 11520*n -2016*n^2 -198296*n^3 +33012*n^4 +2199246*n^5 +9547461*n^6+ 6331782*n^7 +1994265*n^8 +362474*n^9 +39375*n^10 +2394*n^11 +63*n^12)/2903040
		

Crossrefs

A000012, A000096, A163943 and A163944 are the first four left hand columns of A163940.
Cf. A053657 (Minkowski), A163402 and A075264.

Programs

  • Maple
    pmax:=6; nmax:=70; with(genfunc): A053657 := proc(n) local P, p, q, s, r; P := select(isprime, [$2..n]); r:=1; for p in P do s := 0: q := p-1; do if q > (n-1) then break fi; s := s + iquo(n-1, q); q := q*p; od; r := r * p^s; od; r end: for px from 1 to nmax do Gf(px):= convert(series(1/((1-(px-1)*x)^2*product((1-k*x), k=1..px-2)),x,nmax+1-px),polynom): for qy from 0 to nmax-px do a(px+qy,qy):=coeff(Gf(px),x,qy) od; od: for p from 1 to pmax do f(x):=0: for ny from p to nmax do f(x):=f(x)+a(ny,p-1)*x^(ny-p) od: f(x):= series(f(x),x, nmax): Gx:=convert(%, ratpoly): rgf_sequence('recur',Gx,x,G,n): a(n,p):=sort(simplify (rgf_expand(Gx,x,n)),n): f(p):=sort(a(n,p)*A053657(p),n,ascending): for k from 0 to 2*p-2 do an(p,k):= coeff(f(p),n,k) od; od: T:=1: for p from 1 to pmax do for k from 0 to 2*p-2 do a(T):=an(p,k): T:=T+1 od: od: seq(a(n),n=1..T-1); for p from 1 to pmax do seq(an(p,k),k=0..2*p-2) od; for p from 1 to pmax do MC(n,p):=sort(a(n,p),n,ascending) od;

A202339 Triangle of numerators of coefficients of the polynomial Q_m(n) defined by the recursion Q_0(n)=1; for m >= 1, Q_m(n) = Sum_{i=1..n} i*Q_(m-1)(i). For m >= 1, the denominator for all 2*m+1 terms of the m-th row is A053657(m+1).

Original entry on oeis.org

1, 1, 1, 0, 3, 10, 9, 2, 0, 1, 7, 17, 17, 6, 0, 0, 15, 180, 830, 1848, 2015, 900, 20, 0, -48, 3, 55, 410, 1598, 3467, 4055, 2120, 52, -240, 0, 0, 63, 1638, 17955, 107954, 387009, 837426, 1038681, 606606, 9828, -113624, -2016, 11520, 0, 9, 315, 4767, 40859, 217973, 747021, 1628877, 2122953, 1344798, -5516, -374024, -2592, 80640, 0, 0
Offset: 0

Author

Keywords

Comments

For the first term c(m) of the m-th row, we have c(m) = A053657(m)/(2*m-2)!!.

Examples

			Q_0 = 1,
Q_1 = (x^2 + x)/2,
Q_2 = (3x^4 + 10x^3 + 9x^2 + 2x)/24,
Q_3 = (x^6 + 7x^5 + 17x^4 + 17x^3 + 6x^2)/48,
Q_4 = (15x^8 + 180x^7 + 830x^6 + 1848x^5 + 2015x^4 + 900x^3 + 20x^2 -48x)/5760,
Q_5 = (3x^10 + 55x^9 + 410x^8 + 1598x^7 + 3467x^6 + 4055x^5 + 2120x^4 + 52x^3 -240x^2)/11520,
Q_6 = (63x^12 + 1638x^11 + 17955x^10 + 107954x^9 + 387009x^8 + 837426x^7 + 1038681x^6 + 606606x^5 + 9828x^4 -113624x^3 -2016x^2 + 11520x)/2903040,
Q_7 = (9x^14 + 315x^13 + 4767x^12 + 40859x^11 + 217973x^10 + 747021x^9 + 1628877x^8 + 2122953x^7 + 1344798x^6 -5516x^5 -374024x^4 -2592x^3 + 80640x^2)/5806080,
Q_8 = (135x^16 + 6120x^15 + 122220x*14 + 1414560x^13 + 10493770x^12 + 52032240x^11 + 173988644x^10 + 384104160x^9 + 522150135x^8 + 351312360x^7 -13192648x^6 -135368640x^5 + 2658160x^4 + 49034880x^3 + 509184x^2 -5806080x)/1393459200.
		

Crossrefs

Programs

  • Mathematica
    A053657[n_] := Product[p^Sum[Floor[(n-1)/((p-1) p^k)], {k, 0, n}], {p, Prime[Range[n]]}]; Q[0, n_] = 1; Q[m_, n_] := Q[m, n] = Sum[i*Q[m-1, i], {i, 1, n}]; Table[A053657[m+1]*CoefficientList[Q[m, n], n] // Reverse, {m, 0, 7}] // Flatten (* Jean-François Alcover, Nov 22 2016 *)

Formula

Q_m(n) = S(n+m, n), where S(k,l) are Stirling numbers of the second kind.
In particular, since S(m+1,1)=1, then Q_m(1)=1.

A075263 Triangle of coefficients of polynomials H(n,x) formed from the first (n+1) terms of the power series expansion of ( -x/log(1-x) )^(n+1), multiplied by n!.

Original entry on oeis.org

1, 1, -1, 2, -3, 1, 6, -12, 7, -1, 24, -60, 50, -15, 1, 120, -360, 390, -180, 31, -1, 720, -2520, 3360, -2100, 602, -63, 1, 5040, -20160, 31920, -25200, 10206, -1932, 127, -1, 40320, -181440, 332640, -317520, 166824, -46620, 6050, -255, 1, 362880, -1814400, 3780000, -4233600, 2739240, -1020600, 204630, -18660, 511, -1
Offset: 0

Author

Paul D. Hanna, Sep 13 2002

Keywords

Comments

Special values: H(n,1)=0, H(2n,2)=0, H(n,-x) ~= ( x/log(1+x) )^(n+1), for x>0. H'(n,1) = -1/n!, where H'(n,x) = d/dx H(n,x).
The zeros of these polynomials are all positive reals >= 1. If we order the zeros of H(n,x), {r_k, k=0..(n-1)}, by magnitude so that r_0 = 1, r_k > r_(k-1), for 0 < k < n, then r_(n-k) = r_k/(r_k - 1) when 0 < k < n, n > 1, where r_(n/2) = 2 for even n.
Also Product_{k=0..(n-1)} r_k = n!, r_(n-1) ~ C 2^n.
I believe that these numbers are the coefficients of the Eulerian polynomials An(z) written in powers of z-1. That is, the sequence is: A0(1); A1(1), A1'(1); A2(1), A2'(1), A2''(1)/2!; A3(1), A3'(1), A3''(1)/2!, A3'''(1)/3!; A4(1), A4'(1), A4''(1)/2!, A4'''(1)/3!, A4''''(1)/4! etc. My convention: A0(z)=z, A1(z)=z, A2(z)=z+z^2, A3(z)=z+4z^2+z^3, A4(z)=z+11z^2+11z^3+z^4, etc. - Louis Zulli (zullil(AT)lafayette.edu), Jan 19 2005
H(n,2) gives 1,-1,0,2,0,-16,0,272,0,-7936,0,..., see A009006. - Philippe Deléham, Aug 20 2007
Row sums are zero except for first row. - Roger L. Bagula, Sep 11 2008
From Groux Roland, May 12 2011: (Start)
Let f(x) = (exp(x)+1)^(-1) then the n-th derivative of f equals Sum_{k=0..n} T(n,k)*(f(x))^(n+1-k).
T(n+1,0) = (n+1)*T(n,0); T(n+1,n+1) = -T(n,n) and for 0 < k < n T(n+1,k) = (n+1-k) * T(n,k) - (n-k+2)*T(n,k-1).
T(n,k) = Sum_{i=0..k} (-1)^(i+k)*(n-i)!*binomial(n-i,k-i)*S(n,n-i) where S(n,k) is a Stirling number of the second kind. (End)

Examples

			H(0,x) = 1
H(1,x) = (1 - 1*x)/1!
H(2,x) = (2 - 3*x + 1*x^2)/2!
H(3,x) = (6 - 12*x + 7*x^2 - 1*x^3)/3!
H(4,x) = (24 - 60*x + 50*x^2 - 15*x^3 + 1*x^4)/4!
H(5,x) = (120 - 360*x + 390*x^2 - 180*x^3 + 31*x^4 - 1*x^5)/5!
H(6,x) = (720 - 2520*x + 3360*x^2 - 2100*x^3 + 602*x^4 - 63*x^5 + 1*x^5)/6!
Triangle begins:
     1;
     1,     -1;
     2,     -3,     1;
     6,    -12,     7,     -1;
    24,    -60,    50,    -15,     1;
   120,   -360,   390,   -180,    31,    -1;
   720,  -2520,  3360,  -2100,   602,   -63,   1;
  5040, -20160, 31920, -25200, 10206, -1932, 127, -1;
		

Crossrefs

Cf. Eulerian numbers (A008292).

Programs

  • GAP
    Flat(List([0..12], n-> List([0..n], k-> Sum([0..n-k], j->
    (-1)^(n-j)*Binomial(n-k,j)*(j+1)^n )))); # G. C. Greubel, Jan 27 2020
  • Magma
    T:= func< n,k | &+[(-1)^(n-j)*Binomial(n-k,j)*(j+1)^n: j in [0..n-k]] >;
    [T(n,k): k in [0..n], n in [0..12]]; // G. C. Greubel, Jan 27 2020
    
  • Maple
    CL := f -> PolynomialTools:-CoefficientList(f,x):
    T_row := n -> `if`(n=0, [1], CL(x^(n+1)*polylog(-n, 1-x))):
    for n from 0 to 6 do T_row(n) od; # Peter Luschny, Sep 28 2017
  • Mathematica
    Table[CoefficientList[x^(n+1)*Sum[k^n*(1-x)^k, {k, 0, Infinity}], x], {n, 0, 10}]//Flatten (* Roger L. Bagula, Sep 11 2008 *)
    p[x_, n_]:= x^(n+1)*PolyLog[-n, 1-x]; Table[CoefficientList[p[x, n], x], {n, 0, 10}]//Flatten (* Roger L. Bagula and Gary W. Adamson, Sep 15 2008 *)
  • PARI
    T(n,k)=if(k<0 || k>n,0,n!*polcoeff((-x/log(1-x+x^2*O(x^n)))^(n+1),k))
    for(n=0,10,for(k=0,n,print1(T(n,k),", "));print(""))
    
  • PARI
    T(n,k)=sum(i=0,n-k,(-1)^(n-i)*binomial(n-k,i)*(i+1)^n)
    for(n=0,10,for(k=0,n,print1(T(n,k),", "));print(""))
    
  • PARI
    /* Using e.g.f. A(x,y): */
    {T(n,k)=local(X=x+x*O(x^n),Y=y+y^2*O(y^(k))); n!*polcoeff(polcoeff(-log(1-(1-exp(-X*Y))/y),n,x),k,y)}
    for(n=0,10,for(k=0,n-1,print1(T(n,k),", "));print(""))
    
  • PARI
    /* Deléham's DELTA: T(n,k) = [x^(n-k)*y^k] P(n,0) */
    {P(n,k)=if(n<0||k<0,0,if(n==0,1, P(n,k-1)+(x*(k\2+1)+y*(-(k\2+1)*((k+1)%2)))*P(n-1,k+1)))}
    {T(n,k)=polcoeff(polcoeff(P(n,0),n-k,x),k,y)}
    for(n=0,10,for(k=0,n,print1(T(n,k),", "));print(""))
    
  • Sage
    def T(n, k): return sum( (-1)^(n-j)*binomial(n-k, j)*(j+1)^n for j in (0..n-k))
    [[T(n, k) for k in (0..n)] for n in (0..12)] # G. C. Greubel, Jan 27 2020
    

Formula

Generated by [1, 1, 2, 2, 3, 3, ...] DELTA [ -1, 0, -2, 0, -3, 0, ...], where DELTA is the operator defined in A084938.
T(n, k) = Sum_{i=0..n-k} (-1)^(n-i)*C(n-k, i)*(i+1)^n; n >= 0, 0 <= k <= n. - Paul D. Hanna, Jul 21 2005
E.g.f.: A(x, y) = -log(1-(1-exp(-x*y))/y). - Paul D. Hanna, Jul 21 2005
p(x,n) = x^(n + 1)*Sum_{k>=0} k^n*(1 - x)^k; t(n,m) = Coefficients(p(x,n)). - Roger L. Bagula, Sep 11 2008
p(x,n) = x^(n + 1)*PolyLog(-n, 1 - x); t(n,m) = coefficients(p(x,n)) for n >= 1. - Roger L. Bagula and Gary W. Adamson, Sep 15 2008

Extensions

Error in one term corrected by Benoit Cloitre, Aug 20 2007

A255616 Table read by antidiagonals, T(n,k) = floor(sqrt(k^n)), n >= 0, k >=1.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 3, 2, 1, 1, 2, 4, 5, 4, 1, 1, 2, 5, 8, 9, 5, 1, 1, 2, 6, 11, 16, 15, 8, 1, 1, 2, 7, 14, 25, 32, 27, 11, 1, 1, 3, 8, 18, 36, 55, 64, 46, 16, 1, 1, 3, 9, 22, 49, 88, 125, 128, 81, 22, 1, 1, 3, 10, 27, 64, 129, 216, 279, 256, 140, 32, 1, 1, 3, 11, 31, 81, 181, 343, 529, 625, 512, 243, 45, 1
Offset: 0

Author

Kival Ngaokrajang, Feb 28 2015

Keywords

Examples

			See table in the links.
		

Programs

  • Mathematica
    T[n_, k_] := Floor[Sqrt[k^n]]; Table[T[k, n + 1 - k], {n, 0, 15}, {k, 0, n}] (* G. C. Greubel, Dec 30 2017 *)
  • PARI
    {for(i=1,20,for(n=0,i-1,a=floor(sqrt((i-n)^n));print1(a,", ")))}

Formula

T(n,k) = floor(sqrt(k^n)), n >= 0, k >=1.

Extensions

Terms a(81) onward added by G. C. Greubel, Dec 30 2017
Showing 1-7 of 7 results.