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A020113
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a(n) = ceiling of Gamma(n + 2/9)/Gamma(2/9).
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2
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1, 1, 1, 1, 2, 9, 43, 267, 1928, 15845, 146123, 1493701, 16762640, 204876709, 2708925369, 38526938569, 586465620431, 9513775620310, 163848357905336, 2985681188497228, 57391427290002262, 1160582196308934616, 24630133277222945727, 547336295049398793928
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OFFSET
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0,5
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LINKS
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FORMULA
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a(n) ~ sqrt(2*Pi)*n^(n-5/18)*exp(-n)/Gamma(2/9) as n -> infinity. - Robert Israel, Jun 07 2015
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EXAMPLE
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Gamma(6 + 2/9) = 176.09917208972649...
Gamma(2/9) = 4.1065795667...
176.09917208972649.../4.1065795667... = 42.8822... hence a(6) = 43.
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MAPLE
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Digits := 64:f := proc(n, x) ceil(GAMMA(n+x)/GAMMA(x)); end;
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MATHEMATICA
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Table[Ceiling[Gamma[n + 2/9]/Gamma[2/9]], {n, 0, 19}] (* Alonso del Arte, Jun 07 2015 *)
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PROG
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(Magma) [Ceiling(Gamma(n + 2/9)/Gamma(2/9)): n in [0..30]]; // Vincenzo Librandi, Jun 08 2015
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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