A124817 Interpolation of A001764(n+1) and A006629(n).

1, 1, 3, 4, 12, 18, 55, 88, 273, 455, 1428, 2448, 7752, 13566, 43263, 76912, 246675, 444015, 1430715, 2601300, 8414640, 15426840, 50067108, 92431584, 300830572, 558685348, 1822766520, 3402497504, 11124755664, 20858916870, 68328754959

Offset

0,3

Comments

A column of number triangle A124816.

Links

Table of n, a(n) for n=0..30.

Formula

a(n)=(1/(2(n+3)))*C(3n/2+3,n/2+1)(1+(-1)^n)+(2/(n+3))*C(3(n+1)/2,(n-1)/2)(1-(-1)^n)

Crossrefs

Sequence in context: A026744 A347257 A123765 * A306005 A124818 A321412

Adjacent sequences: A124814 A124815 A124816 * A124818 A124819 A124820

Keyword

easy,nonn

Author

Paul Barry, Nov 08 2006

Status

approved