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A358387
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a(n) = 3 * h(n - 1) * h(n) for n >= 1, where h(n) = hypergeom([-n, -n], [1], 2), and a(0) = 1.
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3
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1, 9, 117, 2457, 60669, 1620729, 45385461, 1311647913, 38774378493, 1165936210281, 35529105456117, 1094291069720121, 34000718751227133, 1064200845293945433, 33516300131277352821, 1061218377653812515657, 33757038339556757274621, 1078167326486278065165513
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n) ~ 3*sqrt(2) * (1 + sqrt(2))^(4*n) / (8*Pi*n). - Vaclav Kotesovec, Jan 08 2024
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MAPLE
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h := n -> hypergeom([-n, -n], [1], 2):
A358387 := n -> ifelse(n = 0, 1, 3*h(n-1)*h(n)):
seq(simplify(A358387(n)), n = 0..17);
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PROG
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(Python)
def A358387gen() -> Generator:
b, a, n = 1, 3, 1
yield b
while True:
yield 3 * a * b
n += 1
aa = a * (6 * n - 3)
bb = b * (n - 1)
b, a = a, (aa - bb) // n
print([next(A358387) for n in range(18)])
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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