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A091682 Decimal expansion of 2*(18 + sqrt(3)*Pi)/27. 4
1, 7, 3, 6, 3, 9, 9, 8, 5, 8, 7, 1, 8, 7, 1, 5, 0, 7, 7, 9, 0, 9, 7, 9, 5, 1, 6, 8, 3, 6, 4, 9, 2, 3, 4, 9, 6, 0, 6, 3, 1, 2, 5, 8, 3, 2, 9, 0, 9, 4, 9, 7, 9, 0, 5, 6, 8, 2, 1, 9, 6, 6, 5, 2, 3, 0, 8, 4, 7, 1, 8, 1, 8, 0, 2, 8, 0, 7, 8, 6, 4, 0, 8, 1, 8, 6, 9, 4, 4, 4, 1, 8, 2, 4, 9, 0, 2, 2, 5, 9, 7, 4 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also, decimal expansion of Sum_{h >= 0} 1/binomial(2*h,h). [From Renzo Sprugnoli]

LINKS

Table of n, a(n) for n=1..102.

Renzo Sprugnoli, Sums of Reciprocals of the Central Binomial Coefficients, INTEGERS, 6 (2006), #A27, page 9.

Eric Weisstein's World of Mathematics, Factorial Sums

FORMULA

Sum_{n>=0} (n!)^2/(2n)!.

Equals A073016 plus 1. - R. J. Mathar, Sep 08 2008

EXAMPLE

1.736399858718715077909795168364923496063125832909497905682196652308471818...

MATHEMATICA

RealDigits[N[(2 (18 + Pi Sqrt@3))/27, 120]] // First (* Michael De Vlieger, Sep 11 2015 *)

PROG

(PARI) default(realprecision, 2000); 2*(18 + sqrt(3)*Pi)/27 \\ Anders Hellström, Sep 11 2015

CROSSREFS

Cf. A248179: decimal expansion of Sum_{h >= 0} 1/binomial(2*h+1,h).

Sequence in context: A241002 A198425 A246203 * A073016 A238695 A019819

Adjacent sequences:  A091679 A091680 A091681 * A091683 A091684 A091685

KEYWORD

nonn,cons

AUTHOR

Eric W. Weisstein, Jan 28 2004

STATUS

approved

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Last modified August 14 18:32 EDT 2020. Contains 336483 sequences. (Running on oeis4.)