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.

A039756 Triangle of B-analogs of Stirling numbers of 2nd kind.

Original entry on oeis.org

1, 1, 1, 1, 4, 1, 1, 9, 13, 1, 1, 16, 58, 40, 1, 1, 25, 170, 330, 121, 1, 1, 36, 395, 1520, 1771, 364, 1, 1, 49, 791, 5075, 12411, 9219, 1093, 1, 1, 64, 1428, 13776, 58086, 96096, 47188, 3280, 1, 1, 81, 2388, 32340, 209622, 618870, 719860, 239220, 9841, 1
Offset: 0

Views

Author

Ruedi Suter (suter(AT)math.ethz.ch)

Keywords

Comments

This is a variant of A039755 with reflected rows. - Tilman Piesk, Oct 27 2019

Examples

			1;
1,  1;
1,  4,   1;
1,  9,  13,    1;
1, 16,  58,   40,     1;
1, 25, 170,  330,   121,    1;
1, 36, 395, 1520,  1771,  364,    1;
1, 49, 791, 5075, 12411, 9219, 1093,  1;
		

Crossrefs

Cf. A039755.

Programs

  • PARI
    T(n,k)=if(k<0||k>n,0,n!*polcoeff(polcoeff(exp(x*y+(exp(2*x*y+x*O(x^n))-1)/(2*y)),n),k))

Formula

Sum a(n,n-k) x^n*y^k/n! = exp(x + y/2*(exp(2*x) - 1)).
T(n, k) = A039755(n, n-k). - Tilman Piesk, Oct 27 2019