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Search: id:A046180
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A046180 Hexagonal pentagonal numbers. +0
3
1, 40755, 1533776805, 57722156241751, 2172315626468283465, 81752926228785223683195, 3076689623521787481625080301, 115788137209866023854693048367775 (list; graph; listen)
OFFSET

1,2

LINKS

Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.

FORMULA

a(n) = 37634*a(n-1) - a(n-2) + 3136; g.f.: (1+3120*x+15*x^2)/((1-x)*(1-37634*x+x^2)) - Warut Roonguthai (warut822(AT)yahoo.com) Jan 08 2001

a(n+1)=18817*a(n)+1568+1358*(192*a(n)^2+32*a(n)+1)^0.5 - Richard Choulet (richardchoulet(AT)yahoo.fr), Sep 19 2007

a(n)=-(1/12)+(5/16)*sqrt(3)*{[18817+10864*sqrt(3)]^n-[18817-10864*sqrt(3)]^n}+(13/24)*[18817+10864*sqrt(3)]^n+[18817-10864*sqrt(3)]^n }, with n>=0 [From Paolo P. Lava (ppl(AT)spl.at), Nov 25 2008]

CROSSREFS

Cf. A046178, A046179.

Cf. A046178 A046179.

Adjacent sequences: A046177 A046178 A046179 this_sequence A046181 A046182 A046183

Sequence in context: A033984 A090060 A097238 this_sequence A133863 A033532 A047828

KEYWORD

nonn,easy

AUTHOR

Eric Weisstein (eric(AT)weisstein.com)

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Last modified July 4 09:27 EDT 2009. Contains 160562 sequences.


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