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1, 27, 405, 5103, 59049, 649539, 6908733, 71744535, 731794257, 7360989291, 73222472421, 721764371007, 7060738412025, 68630377364883, 663426981193869, 6382625094934119, 61149666232110753, 583701359488329915
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 0..200
David H. Bailey, A Compendium of BBP-Type Formulas for Mathematical Constants, page 14. [From Jaume Oliver Lafont (joliverlafont(AT)gmail.com), Sep 25 2009]
X. Gourdon and P. Sebah, Collection of formulae for log 2
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FORMULA
| G.f.: (1+9*x)/(1-9*x)^2
a(0)=1, a(1)=27, a(n)=18*a(n-1)-81*a(n-2) for n>=2.
sum(n>=0, 1/a(n) ) = (3/2)*log(2).
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PROG
| (PARI) a(n)=(2*n+1)*9^n;
(MAGMA) [(2*n+1)*9^n: n in [0..20]]; // Vincenzo Librandi, Jun 08 2011
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CROSSREFS
| a(n)=A005408(n)*A001019(n). Cf. A096949, A096950, A058962 (2n+1)4^n.
Cf. A154920, A164985, A165132. [From Jaume Oliver Lafont (joliverlafont(AT)gmail.com), Sep 25 2009]
Sequence in context: A125462 A036222 A022655 * A096950 A125484 A022751
Adjacent sequences: A155985 A155986 A155987 * A155989 A155990 A155991
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KEYWORD
| nonn
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AUTHOR
| Jaume Oliver Lafont (joliverlafont(AT)gmail.com), Feb 01 2009
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