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.

A293840 E.g.f.: exp(Sum_{n>=1} A000009(n)*x^n).

Original entry on oeis.org

1, 1, 3, 19, 121, 1041, 10651, 121843, 1575729, 22970881, 366805171, 6365365491, 120044573353, 2430782532049, 52677233993931, 1217023986185491, 29799465317716321, 771272544315151233, 21044341084622337379, 603173026772647474771
Offset: 0

Views

Author

Seiichi Manyama, Oct 17 2017

Keywords

Comments

From Peter Bala, Mar 28 2022: (Start)
The congruence a(n+k) == a(n) (mod k) holds for all n and k.
It follows that the sequence obtained by taking a(n) modulo a fixed positive integer k is periodic with exact period dividing k. For example, the sequence taken modulo 10 becomes [1, 1, 3, 9, 1, 1, 1, 3, 9, 1, ...], a purely periodic sequence with exact period 5.
3 divides a(3*n+2); 9 divides a(9*n+8); 11 divides a(11*n+4); 19 divides a(19*n+3). (End)

Crossrefs

Programs

  • Mathematica
    nmax = 20; CoefficientList[Series[E^Sum[PartitionsQ[k]*x^k, {k, 1, nmax}], {x, 0, nmax}], x] * Range[0, nmax]! (* Vaclav Kotesovec, Oct 18 2017 *)

Formula

a(0) = 1 and a(n) = (n-1)! * Sum_{k=1..n} k*A000009(k)*a(n-k)/(n-k)! for n > 0.

A293839 E.g.f.: exp(Sum_{n>=1} A000009(n)*x^n/n).

Original entry on oeis.org

1, 1, 2, 8, 38, 238, 1828, 16096, 160604, 1826684, 23018264, 316422304, 4755059848, 77084268712, 1343682876272, 25097562397952, 498130253334032, 10479084018025744, 233353674153699616, 5470193826634531456, 134766983204541259616, 3482705318091355591136
Offset: 0

Views

Author

Seiichi Manyama, Oct 17 2017

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 20; CoefficientList[Series[E^Sum[PartitionsQ[k]*x^k/k, {k, 1, nmax}], {x, 0, nmax}], x] * Range[0, nmax]! (* Vaclav Kotesovec, Oct 18 2017 *)

Formula

a(0) = 1 and a(n) = (n-1)! * Sum_{k=1..n} A000009(k)*a(n-k)/(n-k)! for n > 0.

A293908 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of e.g.f.: exp(Sum_{j>=1} j^(k-1)*A000009(j)*x^j).

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 1, 3, 8, 1, 1, 5, 19, 38, 1, 1, 9, 49, 121, 238, 1, 1, 17, 133, 409, 1041, 1828, 1, 1, 33, 373, 1441, 4841, 10651, 16096, 1, 1, 65, 1069, 5233, 23601, 66541, 121843, 160604, 1, 1, 129, 3109, 19441, 119441, 442681, 1006825, 1575729, 1826684, 1, 1
Offset: 0

Views

Author

Seiichi Manyama, Oct 19 2017

Keywords

Examples

			Square array begins:
     1,    1,    1,     1,      1, ...
     1,    1,    1,     1,      1, ...
     2,    3,    5,     9,     17, ...
     8,   19,   49,   133,    373, ...
    38,  121,  409,  1411,   5233, ...
   238, 1041, 4841, 23601, 119441, ...
		

Crossrefs

Columns k=0..2 give A293839, A293840, A293841.
Rows n=0-1 give A000012.
Cf. A293796.

Formula

A(0,k) = 1 and A(n,k) = (n-1)! * Sum_{j=1..n} j^k*A000009(j)*A(n-j,k)/(n-j)! for n > 0.
Showing 1-3 of 3 results.