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 1-3 of 3 results.

A098437 Row sums in triangle of 3rd central factorial numbers (A098436).

Original entry on oeis.org

1, 2, 11, 111, 1732, 41153, 1361023, 59661972, 3400514643, 244686040585, 21672428066346, 2327934086035165, 299095824104595685, 45325168774732866658, 8011977427652269129031
Offset: 0

Views

Author

Ralf Stephan, Sep 08 2004

Keywords

Programs

  • PARI
    {a(n)=polcoeff(sum(m=0, n, x^m/prod(k=1,m+1,1-k^3*x +x*O(x^n))), n)} /* Paul D. Hanna, Feb 15 2012 */

Formula

O.g.f.: Sum_{n>=0} x^n / Product_{k=1..n+1} (1-k^3*x). [From Paul D. Hanna, Feb 15 2012]
G.f.: (1 - G(0) )/(1-x) where G(k) =1 - 1/(1 - x*k^3)/(1-x/(x-1/G(k+1) )); (recursively defined continued fraction). - Sergei N. Gladkovskii, Jan 17 2013

A269948 Triangle read by rows, Stirling set numbers of order 3, T(n,n) = 1, T(n,k) = 0 if k<0 or k>n, otherwise T(n,k) = T(n-1,k-1)+k^3*T(n-1, k), for n>=0 and 0<=k<=n.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 1, 9, 1, 0, 1, 73, 36, 1, 0, 1, 585, 1045, 100, 1, 0, 1, 4681, 28800, 7445, 225, 1, 0, 1, 37449, 782281, 505280, 35570, 441, 1, 0, 1, 299593, 21159036, 33120201, 4951530, 130826, 784, 1
Offset: 0

Views

Author

Peter Luschny, Mar 22 2016

Keywords

Comments

Also called 3rd central factorial numbers.

Examples

			1,
0, 1,
0, 1, 1,
0, 1, 9,     1,
0, 1, 73,    36,     1,
0, 1, 585,   1045,   100,    1,
0, 1, 4681,  28800,  7445,   225,   1,
0, 1, 37449, 782281, 505280, 35570, 441, 1.
		

Crossrefs

Variant: A098436.
Cf. A007318 (order 0), A048993 (order 1), A269945 (order 2).

Programs

  • Maple
    T := proc(n, k) option remember;
        `if`(n=k, 1,
        `if`(k<0 or k>n, 0,
         T(n-1, k-1) + k^3*T(n-1, k))) end:
    for n from 0 to 9 do seq(T(n,k), k=0..n) od;
  • Mathematica
    T[n_, n_] = 1; T[n_, k_] /; 0 <= k <= n := T[n, k] = T[n - 1, k - 1] + k^3*T[n - 1, k]; T[, ] = 0;
    Table[T[n, k], {n, 0, 8}, {k, 0, n}] // Flatten (* Jean-François Alcover, Jul 25 2019 *)

Formula

T(n,2) = (8^(n-1)-1)/7 for n>=1 (cf. A023001).
T(n,n-1) = (n*(n-1)/2)^2 for n>=1 (cf. A000537).
Row sums: A098437.

A351800 a(n) = [x^n] 1/Product_{j=1..n} (1 - j^3*x).

Original entry on oeis.org

1, 1, 73, 28800, 33120201, 83648533275, 393764054984212, 3103381708489548640, 37965284782803741391413, 681476650259874114533077575, 17184647574689079046814198039765, 588057239856779143071625300022102376, 26548105106818292578525347802793561068860
Offset: 0

Views

Author

Alois P. Heinz, Feb 19 2022

Keywords

Examples

			a(2) = (1*1)^3 + (1*2)^3 + (2*2)^3 = 1 + 8 + 64 = 73.
		

Crossrefs

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(k=0, 1,
          add(b(j, k-1)*j^3, j=1..n))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..15);
  • Mathematica
    Table[SeriesCoefficient[Product[1/(1 - k^3*x), {k, 1, n}], {x, 0, n}], {n, 0, 15}] (* Vaclav Kotesovec, May 17 2025 *)

Formula

a(n) = Sum_{p in {1..n}^n : p_i <= p_{i+1}} Product_{j=1..n} p_j^3.
a(n) = A098436(2n-1,n-1) = A269948(2n,n).
a(n) ~ c * d^n * n^(3*n - 1/2), where d = 1.54371040458513693750053812318801418996889528987425... and c = 0.71526493063554190404119140313248864511356727815244... - Vaclav Kotesovec, May 13 2025
Showing 1-3 of 3 results.