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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A072605 Number of necklaces with n beads over an n-ary alphabet {a1,a2,...,an} such that #(w,a1) >= #(w,a2) >= ... >= #(w,ak) >= 0, where #(w,x) counts the letters x in word w.

Original entry on oeis.org

1, 1, 2, 4, 13, 50, 270, 1641, 11945, 96784, 887982, 8939051, 99298354, 1195617443, 15619182139, 219049941201, 3293800835940, 52746930894774, 897802366250126, 16167544246362567, 307372573011579188, 6148811682561390279, 129164845357784003661
Offset: 0

Views

Author

Wouter Meeussen, Aug 06 2002

Keywords

Crossrefs

Programs

  • Mathematica
    neck[li:{__Integer}] := Module[{n, d}, n=Plus@@li; d=n-First[li]; Fold[ #1+(EulerPhi[ #2]*(n/#2)!)/Times@@((li/#2)!)&, 0, Divisors[GCD@@li]]/n]; Table[ Plus@@(neck /@ IntegerPartitions[n]), {n, 24}]
  • PARI
    a(n)={if(n==0, 1, my(p=prod(k=1, n, 1/(1-x^k/k!) + O(x*x^n))); sumdiv(n, d, eulerphi(n/d)*d!*polcoeff(p,d))/n)} \\ Andrew Howroyd, Dec 20 2017

Formula

a(n) = (1/n) * Sum_{d|n} phi(n/d) * A005651(d) for n > 0. - Andrew Howroyd, Sep 25 2017
See Mathematica line.
a(n) ~ c * (n-1)!, where c = Product_{k>=2} 1/(1-1/k!) = A247551 = 2.52947747207915264818011615... . - Vaclav Kotesovec, Aug 27 2015

Extensions

a(0)=1 prepended by Alois P. Heinz, Aug 23 2015
Name changed by Andrew Howroyd, Sep 25 2017

A185895 Exponential generating function is (1-x^1/1!)(1-x^2/2!)(1-x^3/3!)....

Original entry on oeis.org

1, -1, -1, 2, 3, 14, -40, -43, -357, -1762, 8004, 13067, 78540, 492439, 3932305, -26867293, -44643557, -363632466, -1729625764, -15939972937, -145669871232, 1488599170613, 3515325612655, 26765194180353, 151925998229148
Offset: 0

Views

Author

Michael Somos, Feb 05 2011

Keywords

Comments

From Peter Bala, Mar 17 2022: (Start)
Conjectures: 1) a(n) differs in sign from a(n-1) iff n is a triangular number (checked up to n = 1225 = (50*51)/2)
2) The same property holds for the coefficients of A(x)^2, the square of the o.g.f. A(x) = 1 - x - x^2 + 2*x^3 + 3*x^4 + ... : A(x)^2 = 1 - 2*x - x^2 + 6*x^3 + 3*x^4 + 18*x^5 - 110*x^6 - 22*x^7 - 483*x^8 - 2800*x^9 + 20030*x^10 + ....
3) The Gauss congruences a(n*p^k) == a(n*p^(k-1)) (mod p^k) hold for all primes p and positive integers n and k. (End)

Crossrefs

Programs

  • PARI
    {a(n) = if( n<0, 0, n! * polcoeff( prod( k=1, n, 1 - x^k / k!, 1 + x * O(x^n)), n))}
    
  • PARI
    {a(n)=if(n<0,0,if(n==0,1,sum(k=1,n,(n-1)!/(n-k)!*a(n-k)*sumdiv(k,d,-d*d!^(-k/d)))))} [Hanna]

Formula

E.g.f.: Product_{k>0} (1 - x^k/k!).
a(n) = Sum_{k=1..n} (n-1)!/(n-k)!*b(k)*a(n-k), where b(k) = Sum_{d divides k} -d*d!^(-k/d) and a(0) = 1 [cf. Vladeta Jovovic's formula in A007837].
E.g.f.: exp(-Sum_{k>=1} Sum_{j>=1} x^(j*k)/(k*(j!)^k)). - Ilya Gutkovskiy, Jun 18 2018

A321750 Irregular triangle read by rows where T(H(u),H(v)) is the coefficient of m(v) in p(u), where H is Heinz number, m is monomial symmetric functions, and p is power sum symmetric functions.

Original entry on oeis.org

1, 1, 1, 0, 1, 2, 1, 0, 0, 1, 1, 0, 1, 0, 0, 0, 0, 1, 3, 6, 1, 2, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 2, 2, 2, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 6, 4, 12, 24, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
Offset: 1

Views

Author

Gus Wiseman, Nov 20 2018

Keywords

Comments

Row n has length A000041(A056239(n)).
The Heinz number of an integer partition (y_1, ..., y_k) is prime(y_1) * ... * prime(y_k).

Examples

			Triangle begins:
   1
   1
   1   0
   1   2
   1   0   0
   1   1   0
   1   0   0   0   0
   1   3   6
   1   2   0   0   0
   1   0   1   0   0
   1   0   0   0   0   0   0
   1   2   2   2   0
   1   0   0   0   0   0   0   0   0   0   0
   1   1   0   0   0   0   0
   1   0   1   0   0   0   0
   1   6   4  12  24
   1   0   0   0   0   0   0   0   0   0   0   0   0   0   0
   1   1   2   2   0   0   0
For example, row 18 gives: p(221) = m(5) + 2m(32) + m(41) + 2m(221).
		

Crossrefs

A183235 Sums of the cubes of multinomial coefficients.

Original entry on oeis.org

1, 1, 9, 244, 15833, 1980126, 428447592, 146966837193, 75263273895385, 54867365927680618, 54868847079435960134, 73030508546599681432983, 126197144644287414997433576, 277255161467330877411064074059
Offset: 0

Views

Author

Paul D. Hanna, Jan 04 2011

Keywords

Comments

Equals sums of the cubes of terms in rows of the triangle of multinomial coefficients (A036038).
Ignoring initial term, equals the logarithmic derivative of A182963.

Examples

			G.f.: A(x) = 1 + x + 9*x^2/2!^3 + 244*x^3/3!^3 + 15833*x^4/4!^3 +...
A(x) = 1/((1-x)*(1-x^2/2!^3)*(1-x^3/3!^3)*(1-x^4/4!^3)*...).
...
After the initial term a(0)=1, the next few terms are
a(1) = 1^3 = 1,
a(2) = 1^3 + 2^3 = 9,
a(3) = 1^3 + 3^3 + 6^3 = 244,
a(4) = 1^3 + 4^3 + 6^3 + 12^3 + 24^3 = 15833,
a(5) = 1^3 + 5^3 + 10^3 + 20^3 + 30^3 + 60^3 + 120^3 = 1980126, ...;
and continue with the sums of cubes of the terms in triangle A036038.
		

Crossrefs

Programs

  • PARI
    {a(n)=n!^3*polcoeff(1/prod(k=1, n, 1-x^k/k!^3 +x*O(x^n)), n)}

Formula

G.f.: Sum_{n>=0} a(n)*x^n/n!^3 = Product_{n>=1} 1/(1 - x^n/n!^3).
a(n) ~ c * (n!)^3, where c = Product_{k>=2} 1/(1-1/(k!)^3) = 1.14825648754771664323845829539510031170864046029463094659207423270573478812675... . - Vaclav Kotesovec, Feb 19 2015

Extensions

Examples added and name changed by Paul D. Hanna, Jan 05 2011

A325305 Irregular triangular array, read by rows: T(n,k) is the sum of the products of distinct multinomial coefficients (n_1 + n_2 + n_3 + ...)!/(n_1! * n_2! * n_3! * ...) taken k at a time, where (n_1, n_2, n_3, ...) runs over all integer partitions of n (n >= 0, 0 <= k <= A070289(n)).

Original entry on oeis.org

1, 1, 1, 1, 1, 3, 2, 1, 10, 27, 18, 1, 47, 718, 4416, 10656, 6912, 1, 246, 20545, 751800, 12911500, 100380000, 304200000, 216000000, 1, 1602, 929171, 260888070, 39883405500, 3492052425000, 177328940580000, 5153150631600000, 82577533320000000, 669410956800000000, 2224399449600000000, 1632586752000000000, 1, 11271
Offset: 0

Views

Author

Petros Hadjicostas, Sep 05 2019

Keywords

Comments

This array was inspired by R. H. Hardin's recurrences for the columns of array A212855. Row n has length A070289(n) + 1.
This array differs from array A309951 starting at row n = 7. Array A309951 calculates a similar sum of products of multinomial coefficients, but the multinomial coefficients do not have to be distinct. Row n of array A309951 has length A000041(n) + 1, i.e., one more than the number of partitions of n.
Let P_n be the set of all lists a = (a_1, a_2,..., a_n) of integers a_i >= 0, i = 1,..., n such that 1*a_1 + 2*a_2 + ... + n*a_n = n; i.e., P_n is the set all integer partitions of n. (We use a different notation for partitions than the one in the name of T(n,k).) Then |P_n| = A000041(n) for n >= 0.
For n = 1..6, all the multinomial coefficients n!/((1!)^a_1 * (2!)^a_2 * ... * (n!)^a^n) corresponding to lists (a_1,...,a_n) in P_n are distinct; that is, A000041(n) = A070289(n) for n = 1..6.
For n = 7, the partitions (a_1, a_2, a_3, a_4, a_5, a_6, a_7) = (0, 2, 1, 0, 0, 0, 0) (i.e., 2 + 2 + 3) and (a_1, a_2, a_3, a_4, a_5, a_6, a_7) = (3, 0, 0, 1, 0, 0, 0) (i.e., 1 + 1 + 1 + 4) give the same multinomial coefficient: 210 = 7!/(2!2!3!) = 7!/(1!1!1!4!). Hence, A000041(7) > A070289(7).
Looking at the multinomial coefficients of the integer partitions of n = 8, 9, 10 on pp. 831-832 of Abramowitz and Stegun (1964), we see that, even in these cases, we have A000041(n) > A070289(n).

Examples

			Triangle begins as follows:
  [n=0]: 1,   1;
  [n=1]: 1,   1;
  [n=2]: 1,   3,     2;
  [n=3]: 1,  10,    27,     18;
  [n=4]: 1,  47,   718,   4416,    10656,      6912;
  [n=5]: 1, 246, 20545, 751800, 12911500, 100380000, 304200000, 216000000;
  ...
For example, when n = 3, the integer partitions of 3 are 3, 1+2, 1+1+1, and the corresponding multinomial coefficients are 3!/3! = 1, 3!/(1!2!) = 3, and 3!/(1!1!1!) = 6. They are all distinct. Then T(n=3, k=0) = 1, T(n=3, k=1) = 1 + 3 + 6 = 10, T(n=3, k=2) = 1*3 + 1*6 + 3*6 = 27, and T(n=3, k=3) = 1*3*6 = 18.
Consider the list [1, 7, 21, 35, 42, 105, 140, 210, 420, 630, 840, 1260, 2520, 5040] of the A070289(7) = 15 - 1 = 14 distinct multinomial coefficients corresponding to the 15 integer partitions of 7. Then  T(7,0) = 1, T(7,1) = 11271 (sum of the coefficients), T(7,2) = 46169368 (sum of products of every two different coefficients), T(7,3) = 92088653622 (sum of products of every three different coefficients), and so on. Finally, T(7,14) = 2372695722072874920960000000000 = product of these coefficients.
		

Crossrefs

Programs

  • Maple
    g:= proc(n, i) option remember; `if`(n=0 or i=1, [n!], [{map(x->
          binomial(n, i)*x, g(n-i, min(n-i, i)))[], g(n, i-1)[]}[]])
        end:
    b:= proc(n, m) option remember; `if`(n=0, 1,
          expand(b(n-1, m)*(g(m$2)[n]*x+1)))
        end:
    T:= n->(p->seq(coeff(p, x, i), i=0..degree(p)))(b(nops(g(n$2)), n)):
    seq(T(n), n=0..7);  # Alois P. Heinz, Sep 05 2019
  • Mathematica
    g[n_, i_] := g[n, i] = If[n == 0 || i == 1, {n!}, Union[Map[Function[x, Binomial[n, i] x], g[n - i, Min[n - i, i]]], g[n, i - 1]]];
    b[n_, m_] := b[n, m] = If[n == 0, 1, b[n - 1, m] (g[m, m][[n]] x + 1)];
    T[n_] := CoefficientList[b[Length[g[n, n]], n], x];
    T /@ Range[0, 7] // Flatten (* Jean-François Alcover, May 06 2020, after Maple *)

Formula

Sum_{k=0..A070289(n)} (-1)^k * T(n,k) = 0.

A183236 Sums of multinomial coefficients to the 4th power.

Original entry on oeis.org

1, 1, 17, 1378, 354065, 221300626, 286871431922, 688780254549829, 2821284379712638737, 18510450092641988146882, 185104666826030540618018642, 2710117456989714966261367339909, 56196998736058707145628074314226034
Offset: 0

Views

Author

Paul D. Hanna, Jan 04 2011

Keywords

Comments

Equals sums of the 4th power of terms in rows of the triangle of multinomial coefficients (A036038).

Examples

			G.f.: A(x) = 1 + x + 17*x^2/2!^4 + 1378*x^3/3!^4 + 354065*x^4/4!^4 +...
A(x) = 1/((1-x)*(1-x^2/2!^4)*(1-x^3/3!^4)*(1-x^4/4!^4)*...).
		

Crossrefs

Programs

  • PARI
    {a(n)=n!^4*polcoeff(1/prod(k=1, n, 1-x^k/k!^4 +x*O(x^n)), n)}

Formula

G.f.: Sum_{n>=0} a(n)*x^n/n!^4 = Product_{n>=1} 1/(1 - x^n/n!^4).
a(n) ~ c * (n!)^4, where c = Product_{k>=2} 1/(1-1/(k!)^4) = 1.067493570155257423039762074691753715853526744464586468822554194836450214299287... . - Vaclav Kotesovec, Feb 19 2015

A183237 Sums of multinomial coefficients to the 5th power.

Original entry on oeis.org

1, 1, 33, 8020, 8220257, 25688403126, 199758931567152, 3357348771315829641, 110013706232123658318433, 6496199364012472451887572970, 649619955166586474874295658148158, 104621943411970982740307507415589286391
Offset: 0

Views

Author

Paul D. Hanna, Jan 04 2011

Keywords

Comments

Equals sums of the 5th power of terms in rows of the triangle of multinomial coefficients (A036038).

Examples

			G.f.: A(x) = 1 + x + 33*x^2/2!^5 + 8020*x^3/3!^5 + 8220257*x^4/4!^5 +...
A(x) = 1/((1-x)*(1-x^2/2!^5)*(1-x^3/3!^5)*(1-x^4/4!^5)*...).
		

Crossrefs

Programs

  • PARI
    {a(n)=n!^5*polcoeff(1/prod(k=1, n, 1-x^k/k!^5 +x*O(x^n)), n)}

Formula

G.f.: Sum_{n>=0} a(n)*x^n/n!^5 = Product_{n>=1} 1/(1 - x^n/n!^5).
a(n) ~ c * (n!)^5, where c = Product_{k>=2} 1/(1-1/(k!)^5) = 1.03239096052278897179685563337623849923796538921602982416328969955606263213989... . - Vaclav Kotesovec, Feb 19 2015

A183238 Sums of multinomial coefficients to the 6th power.

Original entry on oeis.org

1, 1, 65, 47386, 194139713, 3033434015626, 141528428949437282, 16650678223240391821765, 4364875648285724481960633921, 2319673879587334552914376906604146, 2319673881714199597935597727665884813690
Offset: 0

Views

Author

Paul D. Hanna, Jan 04 2011

Keywords

Comments

Equals sums of the 6th power of terms in rows of the triangle of multinomial coefficients (A036038).

Examples

			G.f.: A(x) = 1 + x + 65*x^2/2!^6 + 47386*x^3/3!^6 + 194139713*x^4/4!^6 +...
A(x) = 1/((1-x)*(1-x^2/2!^6)*(1-x^3/3!^6)*(1-x^4/4!^6)*...).
		

Crossrefs

Programs

  • PARI
    {a(n)=n!^6*polcoeff(1/prod(k=1, n, 1-x^k/k!^6 +x*O(x^n)), n)}

Formula

G.f.: Sum_{n>=0} a(n)*x^n/n!^6 = Product_{n>=1} 1/(1 - x^n/n!^6).

A309973 Number T(n,k) of colored integer partitions of n using all colors of a k-set such that parts i have distinct color patterns in arbitrary order and each pattern for a part i has i colors in (weakly) increasing order; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 0, 1, 0, 1, 3, 0, 2, 6, 10, 0, 2, 21, 42, 47, 0, 3, 42, 177, 264, 246, 0, 4, 90, 619, 1746, 2095, 1602, 0, 5, 176, 1809, 7556, 16085, 16608, 11481, 0, 6, 348, 5211, 32621, 100030, 171480, 154385, 95503, 0, 8, 640, 13961, 120964, 522890, 1262832, 1842659, 1503232, 871030
Offset: 0

Views

Author

Alois P. Heinz, Sep 21 2019

Keywords

Examples

			T(3,1) = 2: 3aaa, 2aa1a.
T(3,2) = 6: 3aab, 3abb, 2aa1b, 2ab1a, 2ab1b, 2bb1a.
T(3,3) = 10: 3abc, 2ab1c, 2ac1b, 2bc1a, 1a1b1c, 1a1c1b, 1b1a1c, 1b1c1a, 1c1a1b, 1c1b1a.
Triangle T(n,k) begins:
  1;
  0, 1;
  0, 1,   3;
  0, 2,   6,   10;
  0, 2,  21,   42,    47;
  0, 3,  42,  177,   264,    246;
  0, 4,  90,  619,  1746,   2095,   1602;
  0, 5, 176, 1809,  7556,  16085,  16608,  11481;
  0, 6, 348, 5211, 32621, 100030, 171480, 154385, 95503;
  ...
		

Crossrefs

Columns k=0-2 give: A000007, A000009 (for n>0), A327890.
Main diagonal gives A005651.
Row sums give A327679.
T(2n,n) gives A327681.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0, 1,
          `if`(i<1, 0, add(b(n-i*j, min(n-i*j, i-1), k)*
           binomial(binomial(k+i-1, i), j)*j!, j=0..n/i)))
        end:
    T:= (n, k)-> add(b(n$2, i)*(-1)^(k-i)*binomial(k, i), i=0..k):
    seq(seq(T(n, k), k=0..n), n=0..12);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n==0, 1, If[i<1, 0, Sum[b[n - i j, Min[n - i j, i-1], k] Binomial[Binomial[k+i-1, i], j] j!, {j, 0, n/i}]]];
    T[n_, k_] := Sum[b[n, n, i] (-1)^(k - i) Binomial[k, i], {i, 0, k}];
    Table[T[n, k], {n, 0, 12}, {k, 0, n}] // Flatten (* Jean-François Alcover, May 29 2020, after Maple *)

Formula

Sum_{k=1..n} k * T(n,k) = A327680(n).

A327801 Sum T(n,k) of multinomials M(n; lambda), where lambda ranges over all partitions of n into parts incorporating k; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 1, 1, 3, 2, 1, 10, 9, 3, 1, 47, 40, 18, 4, 1, 246, 235, 100, 30, 5, 1, 1602, 1476, 705, 200, 45, 6, 1, 11481, 11214, 5166, 1645, 350, 63, 7, 1, 95503, 91848, 44856, 13776, 3290, 560, 84, 8, 1, 871030, 859527, 413316, 134568, 30996, 5922, 840, 108, 9, 1
Offset: 0

Views

Author

Alois P. Heinz, Sep 25 2019

Keywords

Comments

Here we assume that every list of parts has at least one 0 because its addition does not change the value of the multinomial.

Examples

			Triangle T(n,k) begins:
      1;
      1,     1;
      3,     2,     1;
     10,     9,     3,     1;
     47,    40,    18,     4,    1;
    246,   235,   100,    30,    5,   1;
   1602,  1476,   705,   200,   45,   6,  1;
  11481, 11214,  5166,  1645,  350,  63,  7, 1;
  95503, 91848, 44856, 13776, 3290, 560, 84, 8, 1;
  ...
		

Crossrefs

Columns k=0-2 give: A005651, A327827, A327828.
Row sums give A320566.
T(2n,n) gives A266518.
T(n,n-1) gives A001477.
T(n+1,n-1) gives A045943.
Cf. A327869.

Programs

  • Maple
    with(combinat):
    T:= (n, k)-> add(multinomial(add(i, i=l), l[], 0), l=
                 select(x-> k=0 or k in x, partition(n))):
    seq(seq(T(n, k), k=0..n), n=0..10);
    # second Maple program:
    b:= proc(n, i, k) option remember; `if`(n=0, 1,
          `if`(i<2, 0, b(n, i-1, `if`(i=k, 0, k)))+
          `if`(i=k, 0, b(n-i, min(n-i, i), k)/i!))
        end:
    T:= (n, k)-> n!*(b(n$2, 0)-`if`(k=0, 0, b(n$2, k))):
    seq(seq(T(n, k), k=0..n), n=0..10);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n == 0, 1, If[i < 2, 0, b[n, i - 1, If[i == k, 0, k]]] + If[i == k, 0, b[n - i, Min[n - i, i], k]/i!]];
    T[n_, k_] := n! (b[n, n, 0] - If[k == 0, 0, b[n, n, k]]);
    Table[T[n, k], {n, 0, 10}, {k, 0, n}] // Flatten (* Jean-François Alcover, Apr 30 2020, from 2nd Maple program *)
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