A368369 - OEIS

%I #20 Jan 29 2024 10:50:18

%S 0,4,324,38656,6812500,1691793216,566933589544,247467140448256,

%T 136744348012840296,93452709250000000000,77479910616937022101996,

%U 76677271817228569527975936,89338843947334074736463717884,121104748419604219251183463776256,189040371972603446582336425781250000,336742459165125951045187297509382291456

%N AGM transform of odd numbers.

%C See A368366 for further information.

%H Paolo Xausa, <a href="/A368369/b368369.txt">Table of n, a(n) for n = 1..210</a>

%t A368369[n_] := With[{m = n^n}, m*(m-(2*n-1)!!)];

%t Array[A368369, 20] (* _Paolo Xausa_, Jan 29 2024 *)

%o (PARI) a368369(n) = {my(v=vector(n, i, i+i-1)); vecsum(v)^n - n^n*vecprod(v)}; \\ _Hugo Pfoertner_, Jan 24 2024

%o (Python)

%o from sympy import factorial2

%o def A368369(n): return (m:=n**n)*(m-factorial2((n<<1)-1)) # _Chai Wah Wu_, Jan 25 2024

%Y Cf. A005408, A368366.

%K nonn

%O 1,2

%A _N. J. A. Sloane_, Jan 24 2024