A061787 a(n) = Sum_{k=1..n} (2k-1)^(2k-1).

1, 28, 3153, 826696, 388247185, 285699917796, 303160806510049, 438197051187369424, 827678458937524133601, 1979247334119251113257580, 5844566265720101772494382001, 20886312566113632136127527292568

Offset: 1

Author

Amarnath Murthy, May 25 2001

Keywords

• nonn
• easy

Examples

			a(3) = 1 + 3^3 + 5^5 = 3153.
		

Links

• Harry J. Smith, Table of n, a(n) for n = 1..100

Crossrefs

Partial sums of A085529.

Programs

GAP

List([1..13],n->Sum([1..n],k->(2*k-1)^(2*k-1))); # Muniru A Asiru, Jul 01 2018

Mathematica

Array[Sum[(2 k - 1)^(2 k - 1), {k, #}] &, 12] (* Michael De Vlieger, Jul 01 2018 *)
Accumulate[#^#&/@Range[1,25,2]] (* Harvey P. Dale, Jul 16 2022 *)

PARI

{ a=n=0; forstep (p=1, 200, 2, write("b061787.txt", n++, " ", a+=p^p) ) } \\ Harry J. Smith, Jul 28 2009

Formula

a(n) ~ exp(-1) * 2^(2*n-1) * n^(2*n-1). - Vaclav Kotesovec, Dec 09 2021

Extensions

Corrected and extended by Jason Earls, May 27 2001