A190878 E.g.f. exp(x/(1-x-x^4)).

1, 1, 3, 13, 73, 621, 6211, 70393, 884913, 12534553, 197772931, 3429365061, 64519103353, 1309062244933, 28518573321603, 664268130978481, 16466530506866401, 432644339697987633, 12007970879629419523, 351062850914762411773, 10783262700644774606121

Offset

0,3

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..125

Formula

a(n) = n!*sum(m=0..n, sum(j=0..(n-m)/3, binomial(n-3*j-1,m-1)*binomial(n-m-3*j,j))/m!).

Prog

(Maxima)
a(n):=n!*sum(sum(binomial(n-3*j-1, m-1)*binomial(n-m-3*j, j), j, 0, (n-m)/3)/m!, m, 0, n);
(PARI) Vec(serlaplace(exp(x/(1-x-x^4+O(x^66))))) /* Joerg Arndt, May 24 2011 */

Crossrefs

Sequence in context: A367747 A162161 A119013 * A156154 A334785 A349533

Adjacent sequences: A190875 A190876 A190877 * A190879 A190880 A190881

Keyword

nonn

Author

Vladimir Kruchinin, May 23 2011

Status

approved