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A377239
Expansion of sqrt(1 + 4*x/sqrt(1 - 4*x)).
2
1, 2, 2, 8, 22, 80, 268, 976, 3494, 12896, 47556, 177744, 666236, 2515104, 9525976, 36240032, 138269958, 529193152, 2030242708, 7807266512, 30082317460, 116126074400, 449014896040, 1738805527520, 6742758295900, 26180338089280, 101769629532968, 396031222808096, 1542673037902904
OFFSET
0,2
FORMULA
a(n) = 4^n * Sum_{k=0..n} binomial(1/2,k) * binomial(n-k/2-1,n-k).
PROG
(PARI) a(n) = 4^n*sum(k=0, n, binomial(1/2, k)*binomial(n-k/2-1, n-k));
CROSSREFS
Cf. A377240.
Sequence in context: A130102 A151384 A300460 * A290613 A113464 A353252
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Oct 21 2024
STATUS
approved