A020084 a(n) = floor( Gamma(n + 2/5)/Gamma(2/5) ).

1, 0, 0, 1, 4, 20, 108, 694, 5142, 43193, 406016, 4222569, 48137291, 596902408, 7998492273, 115178288736, 1773745646539, 29089428603255, 506156057696641, 9313271461618195, 180677466355392995, 3685820313650017111

Offset

0,5

Links

G. C. Greubel, Table of n, a(n) for n = 0..449

Maple

Digits:= 64: x:=2/5: f:= proc(n, x) trunc(GAMMA(n+x)/GAMMA(x)); end;
seq(floor(pochhammer(2/5, n)), n = 0..25); # G. C. Greubel, Nov 17 2019

Mathematica

Floor[Pochhammer[2/5, Range[0, 25]]] (* G. C. Greubel, Nov 19 2018 *)

Prog

(PARI) vector(26, n, my(x=2/5); gamma(n-1+x)\gamma(x) ) \\ G. C. Greubel, Nov 19 2018
(Magma) [Truncate(Gamma(n + 2/5)/Gamma(2/5)): n in [0..30]]; // G. C. Greubel, Nov 19 2018
(Sage) [int(gamma(n + 2/5)/gamma(2/5))  for n in range(30)] # G. C. Greubel, Nov 19 2018

Crossrefs

Cf. A020039, A020129.

Cf. A020082, A020083, A020085.

Sequence in context: A377583 A225621 A375303 * A325956 A026127 A222205

Adjacent sequences: A020081 A020082 A020083 * A020085 A020086 A020087

Keyword

nonn

Author

Simon Plouffe

Status

approved