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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A355267 Triangle read by rows, T(n, k) = n! * [y^k] [x^n] exp(1/(1 - x)^(1 + y) - 1), for 0 <= k <= n.

Original entry on oeis.org

1, 1, 1, 3, 5, 2, 13, 29, 21, 5, 73, 200, 202, 90, 15, 501, 1609, 2045, 1295, 410, 52, 4051, 14809, 22418, 18085, 8220, 1998, 203, 37633, 153453, 267400, 259175, 151165, 53095, 10402, 877, 394353, 1767240, 3463612, 3889620, 2740885, 1241632, 353178, 57676, 4140
Offset: 0

Views

Author

Peter Luschny, Jul 05 2022

Keywords

Examples

			Triangle T(n, k) begins:
[0]      1;
[1]      1,      1;
[2]      3,      5,      2;
[3]     13,     29,     21,      5;
[4]     73,    200,    202,     90,     15;
[5]    501,   1609,   2045,   1295,    410,    52;
[6]   4051,  14809,  22418,  18085,   8220,  1998,   203;
[7]  37633, 153453, 267400, 259175, 151165, 53095, 10402, 877;
		

Crossrefs

Cf. A136658 (row sums), A000007 (alternating row sums), A000262 (column 0), A216313 (column 1), A000110 (main diagonal).
Cf. A355260.

Programs

  • Maple
    egf := exp(1/(1 - x)^(1 + y) - 1):
    ser := series(egf, x, 12): cfx := n -> coeff(ser, x, n):
    seq(print(seq(n!*(coeff(cfx(n), y, k)), k = 0..n)), n = 0..8);

A306948 Expansion of e.g.f. (1 + x)*log(1 + x)*exp(x).

Original entry on oeis.org

0, 1, 3, 5, 8, 9, 19, -15, 216, -1407, 11803, -108483, 1106192, -12363703, 150381243, -1977666743, 27965386320, -423158076351, 6822782712723, -116781368777867, 2114916140765496, -40404117909336247, 812091479233464131, -17130720178674680031, 378423227774537955688
Offset: 0

Views

Author

Ilya Gutkovskiy, Mar 17 2019

Keywords

Crossrefs

Programs

  • Maple
    a:=series((1 + x)*log(1 + x)*exp(x),x=0,25): seq(n!*coeff(a, x, n), n=0..24); # Paolo P. Lava, Mar 26 2019
  • Mathematica
    nmax = 24; CoefficientList[Series[(1 + x) Log[1 + x] Exp[x], {x, 0, nmax}], x] Range[0, nmax]!
    Table[Sum[StirlingS1[n, k] BellB[k] k, {k, 0, n}], {n, 0, 24}]
    Table[Sum[(-1)^(k - 1) Binomial[n, k] (n - k + 1) (k - 1)!, {k, 1, n}], {n, 0, 24}]

Formula

a(n) = Sum_{k=0..n} Stirling1(n,k)*A000110(k)*k.
a(n) = Sum_{k=1..n} (-1)^(k-1)*binomial(n,k)*(n - k + 1)*(k - 1)!.
a(n) ~ exp(-1) * (-1)^n * n! / n^2. - Vaclav Kotesovec, Mar 18 2019
Conjecture: D-finite with recurrence a(n) +(n-5)*a(n-1) +(-3*n+10)*a(n-2) +3*(n-3)*a(n-3) +(-n+3)*a(n-4)=0. - R. J. Mathar, Aug 20 2021
Showing 1-2 of 2 results.