A020084 - OEIS

%I #17 Sep 22 2025 16:00:26

%S 1,0,0,1,4,20,108,694,5142,43193,406016,4222569,48137291,596902408,

%T 7998492273,115178288736,1773745646539,29089428603255,506156057696641,

%U 9313271461618195,180677466355392995,3685820313650017111

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

%H G. C. Greubel, <a href="/A020084/b020084.txt">Table of n, a(n) for n = 0..449</a>

%p Digits:= 64: x:=2/5: f:= proc(n,x) trunc(GAMMA(n+x)/GAMMA(x)); end;

%p seq(floor(pochhammer(2/5,n)), n = 0..25); # _G. C. Greubel_, Nov 17 2019

%t Floor[Pochhammer[2/5, Range[0, 25]]] (* _G. C. Greubel_, Nov 19 2018 *)

%o (PARI) vector(26, n, my(x=2/5); gamma(n-1+x)\gamma(x) ) \\ _G. C. Greubel_, Nov 19 2018

%o (Magma) [Truncate(Gamma(n + 2/5)/Gamma(2/5)): n in [0..30]]; // _G. C. Greubel_, Nov 19 2018

%o (SageMath) [int(gamma(n + 2/5)/gamma(2/5))  for n in range(30)] # _G. C. Greubel_, Nov 19 2018

%Y Cf. A020039, A020129.

%Y Cf. A020082, A020083, A020085.

%K nonn

%O 0,5

%A _Simon Plouffe_