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A365252
G.f. satisfies A(x) = 1 + x*A(x)*(1 + x^4*A(x)^2).
1
1, 1, 1, 1, 1, 2, 5, 11, 21, 36, 60, 106, 205, 418, 851, 1685, 3257, 6264, 12210, 24276, 48920, 98873, 199118, 399472, 801361, 1613713, 3266772, 6640770, 13526547, 27564804, 56183565, 114612879, 234187293, 479442918, 983236998, 2018936664, 4149222198
OFFSET
0,6
FORMULA
a(n) = Sum_{k=0..floor(n/5)} binomial(n-4*k,k) * binomial(n-2*k+1,n-4*k)/(n-2*k+1).
PROG
(PARI) a(n) = sum(k=0, n\5, binomial(n-4*k, k)*binomial(n-2*k+1, n-4*k)/(n-2*k+1));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Aug 29 2023
STATUS
approved