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A011248 Twice A000364. 2
2, 2, 10, 122, 2770, 101042, 5405530, 398721962, 38783024290, 4809759350882, 740742376475050, 138697748786275802, 31029068327114173810, 8174145018586247784722 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..13.

G. Almkvist, Many correct digits of Pi, revisited, Amer. Math. Monthly, 104 (1997), 351-353.

J. M. Borwein, Adventures with the OEIS: Five sequences Tony may like, Guttman 70th [Birthday] Meeting, 2015, revised May 2016.

J. M. Borwein, Adventures with the OEIS: Five sequences Tony may like, Guttman 70th [Birthday] Meeting, 2015, revised May 2016. [Cached copy, with permission]

FORMULA

E.g.f.: 2 - 2/Q(0), where Q(k)= 1 - (2*k+1)*(2*k+2)/x + 1/x*(2*k+1)*(2*k+2)/Q(k+1); (continued fraction). - Sergei N. Gladkovskii, May 01 2013

CROSSREFS

Sequence in context: A005613 A005616 A005617 * A069240 A000371 A081088

Adjacent sequences:  A011245 A011246 A011247 * A011249 A011250 A011251

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified December 18 14:22 EST 2018. Contains 318229 sequences. (Running on oeis4.)