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A376718
Expansion of (1 - x + x^4)/((1 - x + x^4)^2 - 4*x^4).
3
1, 1, 1, 1, 4, 11, 22, 37, 61, 114, 232, 467, 894, 1660, 3096, 5893, 11351, 21803, 41535, 78778, 149615, 285100, 544165, 1037963, 1977196, 3764056, 7167911, 13657244, 26027280, 49594720, 94481929, 179981485, 342872893, 653244245, 1244600984, 2371227307
OFFSET
0,5
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).
PROG
(PARI) my(N=40, x='x+O('x^N)); Vec((1-x+x^4)/((1-x+x^4)^2-4*x^4))
(PARI) a(n) = sum(k=0, n\4, binomial(2*n-6*k+1, 2*k));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Oct 02 2024
STATUS
approved