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A375371
Expansion of 1/( (1 + x)^2 * (1 - x*(1 + x)^2) ).
0
1, -1, 4, -1, 11, 7, 35, 52, 138, 267, 606, 1266, 2758, 5882, 12679, 27185, 58442, 125473, 269561, 578929, 1243545, 2670942, 5736984, 12322389, 26467324, 56849060, 122106124, 262271540, 563332877, 1209982051, 2598919376, 5582216323, 11990037159, 25753389147
OFFSET
0,3
FORMULA
a(n) = -a(n-1) + 3*a(n-2) + 6*a(n-3) + 4*a(n-4) + a(n-5).
a(n) = Sum_{k=0..n} binomial(2*k-2,n-k).
PROG
(PARI) my(N=40, x='x+O('x^N)); Vec(1/((1+x)^2*(1-x*(1+x)^2)))
(PARI) a(n) = sum(k=0, n, binomial(2*k-2, n-k));
CROSSREFS
Cf. A375373.
Sequence in context: A183884 A135552 A181690 * A342643 A109088 A060923
KEYWORD
sign
AUTHOR
Seiichi Manyama, Aug 13 2024
STATUS
approved