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URL: https://oeis.org/A383537

⇱ A383537 - OEIS

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A383537
a(n) = Sum_{k=0..floor(n/3)} binomial(n+k,k)^2 * binomial(n-2*k,k).
3
1, 1, 1, 17, 51, 109, 981, 4209, 12637, 79351, 393493, 1454021, 7686459, 39697057, 166999101, 823144689, 4241896917, 19293138685, 93151760599, 473739765167, 2252548154403, 10877558634801, 54682637188009, 266304982300197, 1295171619802551, 6466091747859771
OFFSET
0,4
COMMENTS
Diagonal of the rational function 1 / ((1-x)*(1-y)*(1-z) - z^3).
PROG
(PARI) a(n) = sum(k=0, n\3, binomial(n+k, k)^2*binomial(n-2*k, k));
CROSSREFS
Cf. A383538.
Sequence in context: A005570 A195037 A214660 * A258598 A223906 A146673
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Apr 29 2025
STATUS
approved