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A366100
Expansion of (1/x) * Series_Reversion( x*(1+x-x^4)/(1+x)^4 ).
2
1, 3, 12, 55, 274, 1445, 7942, 45034, 261630, 1549624, 9323622, 56830524, 350196414, 2178046705, 13654823106, 86201572046, 547500090374, 3496124015860, 22431949180480, 144546815784357, 935033560101416, 6069666981214316, 39526168501877736
OFFSET
0,2
FORMULA
a(n) = (1/(n+1)) * Sum_{k=0..floor(n/4)} binomial(n+k,k) * binomial(3*n-k+3,n-4*k).
PROG
(PARI) a(n) = sum(k=0, n\4, binomial(n+k, k)*binomial(3*n-k+3, n-4*k))/(n+1);
CROSSREFS
Sequence in context: A369159 A216493 A216494 * A342283 A120920 A179487
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Sep 29 2023
STATUS
approved