A222621 a(n) = (2n-1)^(2n).

1, 81, 15625, 5764801, 3486784401, 3138428376721, 3937376385699289, 6568408355712890625, 14063084452067724991009, 37589973457545958193355601, 122694327386105632949003612841, 480250763996501976790165756943041, 2220446049250313080847263336181640625

Offset: 1

Author

Dave Durgin, Feb 26 2013

Keywords

• nonn
• easy

Examples

			1^2; 3^4; 5^6; 7^8 and so on.
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..190

Crossrefs

Cf. A005408, A005843, A085535, A338168.

Programs

Magma

[(2*n - 1)^(2*n): n in [1..13]]; // Vincenzo Librandi, Feb 26 2013

Mathematica

Table[(2 n - 1)^(2 n), {n, 20}] (* T. D. Noe, Feb 26 2013 *)

PARI

a(n)=(2*n-1)^(2*n) \\ Charles R Greathouse IV, Aug 20 2013

Formula

a(n) = A005408(n-1)^A005843(n). - Michel Marcus, Apr 14 2018

Sum_{n>=1} 1/a(n) = A338168. - Amiram Eldar, Nov 29 2020