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A086894 a(n) = (A000522(2*n) + 1)/2. 1
1, 3, 33, 979, 54801, 4932051, 651030673, 118487582403, 28437019776609, 8701728051642211, 3306656659624040001, 1527675376746306480243, 843276807963961177093873, 548129925176574765111017139, 414386223433490522423928956721, 360516014387136754508818192346851 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Andrew Howroyd, Table of n, a(n) for n = 0..100

FORMULA

a(n) = (1 + (2*n)!*Sum_{k=0..2*n} 1/k!)/2. - Andrew Howroyd, Jan 05 2020

PROG

(PARI) a(n)={(1 + sum(k=0, 2*n, (2*n)!/k!))/2} \\ Andrew Howroyd, Jan 05 2020

CROSSREFS

Cf. A000522.

Sequence in context: A126466 A002112 A055549 * A255930 A255883 A215948

Adjacent sequences:  A086891 A086892 A086893 * A086895 A086896 A086897

KEYWORD

nonn

AUTHOR

Vladeta Jovovic, Aug 22 2003

EXTENSIONS

Terms a(11) and beyond from Andrew Howroyd, Jan 05 2020

STATUS

approved

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Last modified June 24 21:50 EDT 2021. Contains 345433 sequences. (Running on oeis4.)