The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A358387 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A358387

a(n) = 3 * h(n - 1) * h(n) for n >= 1, where h(n) = hypergeom([-n, -n], [1], 2), and a(0) = 1.
(history; published version)

#8 by Vaclav Kotesovec at Mon Jan 08 05:24:07 EST 2024

STATUS

editing

approved

#7 by Vaclav Kotesovec at Mon Jan 08 05:24:01 EST 2024

FORMULA

a(n) ~ 3*sqrt(2) * (1 + sqrt(2))^(4*n) / (8*Pi*n). - Vaclav Kotesovec, Jan 08 2024

STATUS

approved

editing

#6 by Peter Luschny at Tue Nov 15 09:13:34 EST 2022

STATUS

editing

approved

#5 by Peter Luschny at Tue Nov 15 09:10:32 EST 2022

NAME

qwer

a(n) = 3 * h(n - 1) * h(n) for n >= 1, where h(n) = hypergeom([-n, -n], [1], 2), and a(0) = 1.

CROSSREFS

Cf. A358388.

#4 by Peter Luschny at Tue Nov 15 09:07:37 EST 2022

MAPLE

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);

#3 by Peter Luschny at Tue Nov 15 09:00:22 EST 2022

NAME

allocated for Peter Luschny

qwer

DATA

1, 9, 117, 2457, 60669, 1620729, 45385461, 1311647913, 38774378493, 1165936210281, 35529105456117, 1094291069720121, 34000718751227133, 1064200845293945433, 33516300131277352821, 1061218377653812515657, 33757038339556757274621, 1078167326486278065165513

OFFSET

0,2

PROG

(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

A358387 = A358387gen()

print([next(A358387) for n in range(18)])

KEYWORD

allocated

nonn

AUTHOR

Peter Luschny, Nov 15 2022

STATUS

approved

editing

#2 by Peter Luschny at Sun Nov 13 05:19:10 EST 2022

KEYWORD

allocating

allocated

#1 by Peter Luschny at Sun Nov 13 05:19:10 EST 2022

NAME

allocated for Peter Luschny

KEYWORD

allocating

STATUS

approved