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A124817
Interpolation of A001764(n+1) and A006629(n).
2
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.
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
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Nov 08 2006
STATUS
approved