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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A354978 a(n) = Sum_{k=0..n} Stirling2(k + n, n), row sums of A354977.

Original entry on oeis.org

1, 2, 11, 122, 2127, 50682, 1528900, 55742458, 2381375519, 116597648906, 6434959707871, 395148541757400, 26718459567126420, 1972367532078679140, 157829428196155580220, 13607551212801836305770, 1257482733143493065605455, 123990702648155791823769270, 12993254659661472801817366105
Offset: 0

Views

Author

Peter Luschny, Jun 15 2022

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Sum[StirlingS2[k + n, n], {k,0,n}], {n,0,20}] (* Vaclav Kotesovec, Jun 15 2022 *)

Formula

a(n) ~ 2^(2*n) * n^(n-1/2) / (sqrt(2*Pi*(1-c)) * exp(n) * c^n * (2-c)^n), where c = -LambertW(-2*exp(-2)) = -A226775. - Vaclav Kotesovec, Jun 15 2022

A354797 Triangle read by rows. T(n, k) = |Stirling1(n, k)| * Stirling2(n + k, n) = A132393(n, k) * A048993(n + k, n).

Original entry on oeis.org

1, 0, 1, 0, 3, 7, 0, 12, 75, 90, 0, 60, 715, 2100, 1701, 0, 360, 7000, 36750, 69510, 42525, 0, 2520, 72884, 595350, 1940295, 2692305, 1323652, 0, 20160, 814968, 9549120, 47030445, 109794300, 120023904, 49329280, 0, 181440, 9801000, 156008160, 1076453763, 3723239520, 6733767040, 6065579520, 2141764053
Offset: 0

Views

Author

Peter Luschny, Jun 06 2022

Keywords

Examples

			Table T(n, k) begins:
[0] 1
[1] 0,     1
[2] 0,     3,      7
[3] 0,    12,     75,      90
[4] 0,    60,    715,    2100,     1701
[5] 0,   360,   7000,   36750,    69510,     42525
[6] 0,  2520,  72884,  595350,  1940295,   2692305,   1323652
[7] 0, 20160, 814968, 9549120, 47030445, 109794300, 120023904, 49329280
		

Crossrefs

Programs

  • Maple
    T := (n, k) -> abs(Stirling1(n, k))*Stirling2(n + k, n):
    for n from 0 to 6 do seq(T(n, k), k = 0..n) od;

Formula

Sum_{k=0..n} (-1)^(n - k)*T(n, k) = n^n. - Werner Schulte, Jun 03 2022 in A000312. [Formerly a conjecture, now proved by Mike Earnest, see link.]
T(n, k) = A132393(n, k) * A354977(n, k) = (1/n!) * Sum_{j=0..n} (-1)^(j + k) * binomial(n, j) * Stirling1(n, k) * j^(n + k).
Showing 1-2 of 2 results.