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A308717 Decimal expansion of cosh(sqrt(3)*Pi/2)*sech(Pi/2). 1
3, 0, 4, 0, 1, 9, 1, 5, 5, 1, 6, 4, 2, 5, 5, 3, 0, 7, 5, 6, 0, 1, 8, 6, 0, 0, 2, 7, 9, 0, 0, 7, 5, 7, 2, 3, 3, 8, 2, 3, 8, 5, 4, 9, 0, 5, 8, 7, 9, 1, 7, 1, 6, 7, 7, 9, 4, 1, 6, 5, 9, 7, 5, 1, 8, 4, 0, 8, 8, 5, 3, 9, 2, 5, 2, 3, 3, 2, 0, 4, 4, 1, 9, 6, 5, 1, 4, 6, 1, 8, 2, 9, 9, 0, 2, 5, 5, 0, 2, 1, 9, 7, 1, 1, 2, 0, 4, 8, 3, 0, 3, 9, 2, 2, 3, 1, 0, 5, 0, 6 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..120.

FORMULA

Equals Product_{k>=0} (1 + 1/(2*k*(k + 1) + 1)).

Equals Product_{k>=0} (1 + 1/A001844(k)).

EXAMPLE

3.040191551642553075601860027900757233823854905879...

MATHEMATICA

RealDigits[Cosh[Sqrt[3] Pi/2] Sech[Pi/2], 10, 120][[1]]

PROG

(PARI) cosh(sqrt(3)*Pi/2)/cosh(Pi/2) \\ Michel Marcus, Jun 20 2019

CROSSREFS

Cf. A001844, A156648, A308642, A308718.

Sequence in context: A136667 A004588 A272474 * A297217 A218859 A246691

Adjacent sequences:  A308714 A308715 A308716 * A308718 A308719 A308720

KEYWORD

nonn,cons

AUTHOR

Ilya Gutkovskiy, Jun 19 2019

STATUS

approved

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Last modified September 21 22:00 EDT 2019. Contains 327283 sequences. (Running on oeis4.)