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A286286 a(0) = 0; thereafter, a(n) = (2*n-1)*a(n-1) + 1. 2
0, 1, 4, 21, 148, 1333, 14664, 190633, 2859496, 48611433, 923617228, 19395961789, 446107121148, 11152678028701, 301122306774928, 8732546896472913, 270708953790660304, 8933395475091790033, 312668841628212651156, 11568747140243868092773 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..404

FORMULA

a(n) = (2*n-1)!! * Sum_{k=1..n} 1/(2*k-1)!!. - Seiichi Manyama, Sep 02 2017

CROSSREFS

Conjectured to give indices of records in A132424.

Cf. A001147, A002627 (similar sequence).

Sequence in context: A163861 A247054 A006153 * A277505 A183387 A324236

Adjacent sequences:  A286283 A286284 A286285 * A286287 A286288 A286289

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, May 15 2017

STATUS

approved

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Last modified September 15 18:22 EDT 2019. Contains 327082 sequences. (Running on oeis4.)