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A376786
Expansion of (1 + x - x^4)/((1 + x - x^4)^2 - 4*x).
1
1, 3, 5, 7, 10, 21, 48, 99, 183, 326, 602, 1165, 2282, 4396, 8318, 15675, 29743, 56841, 108765, 207510, 394809, 750880, 1429845, 2725685, 5196420, 9901692, 18859649, 35921156, 68432064, 130388316, 248437405, 473322419, 901717453, 1717851555, 3272777450
OFFSET
0,2
FORMULA
a(n) = 2*a(n-1) - a(n-2) + 2*a(n-4) + 2*a(n-5) - a(n-8).
a(n) = Sum_{k=0..floor(n/4)} binomial(2*n-6*k+1,2*k+1).
PROG
(PARI) my(N=40, x='x+O('x^N)); Vec((1+x-x^4)/((1+x-x^4)^2-4*x))
(PARI) a(n) = sum(k=0, n\4, binomial(2*n-6*k+1, 2*k+1));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Oct 04 2024
STATUS
approved