OFFSET
0,4
COMMENTS
Diagonal sums of A110518.
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..930
FORMULA
a(n) = Sum_{k=0..floor(n/2)} (k/(n-k))*C(2*n-3*k-1, n-2*k)*3^(n-2*k).
MATHEMATICA
Join[{1}, Table[Sum[(k/(n - k))*Binomial[2*n - 3*k - 1, n - 2*k]*3^(n - 2*k), {k, 0, Floor[n/2]}], {n, 1, 50}]] (* G. C. Greubel, Aug 30 2017 *)
PROG
(PARI) concat([1], for(n=1, 25, print1(sum(k=0, n\2, (k/(n - k))*binomial(2*n - 3*k - 1, n - 2*k)*3^(n - 2*k)), ", "))) \\ G. C. Greubel, Aug 30 2017
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Jul 24 2005
STATUS
approved