A026389 a(n) = number of integer strings s(0),...,s(n) counted by array T in A026386 that have s(n)=4; also a(n) = T(2n,n-2).

1, 8, 49, 272, 1440, 7428, 37730, 189808, 948909, 4724160, 23453001, 116207424, 575036475, 2842936320, 14046869575, 69378730880, 342590699955, 1691519468760, 8351553940355, 41235710124400, 203617691311370, 1005560117623204

Offset

2,2

Comments

Binomial transform of A002694. - Ross La Haye, Mar 05 2005

Links

Table of n, a(n) for n=2..23.

Formula

Conjecture: (n+2)*a(n) +4*(-3*n-2)*a(n-1) +2*(24*n-19)*a(n-2) +4*(-18*n+43)*a(n-3) +35*(n-4)*a(n-4)=0. - R. J. Mathar, May 29 2013

Crossrefs

Sequence in context: A166789 A081901 A283686 * A005059 A026719 A026774

Adjacent sequences: A026386 A026387 A026388 * A026390 A026391 A026392

Keyword

nonn

Author

Clark Kimberling

Status

approved