A138439 a(n) = (prime(n)^5 - prime(n)^4)/2.

8, 81, 1250, 7203, 73205, 171366, 668168, 1172889, 3078251, 9901934, 13852815, 33734898, 56515220, 71794821, 112232663, 205152506, 351403469, 415375230, 664986993, 889408835, 1022336676, 1519053159, 1945791161, 2760658604, 4249405488, 5203020050, 5740094931, 6947218853

Offset: 1

Author

Artur Jasinski, Mar 19 2008

Keywords

• nonn
• easy

Crossrefs

Cf. A138407.

Programs

Maple

a:= n-> (p-> p^4*(p-1)/2)(ithprime(n)):
seq(a(n), n=1..28);  # Alois P. Heinz, Jun 14 2025

Mathematica

a[n_]:=(Prime[n]^5-Prime[n]^4)/2; Array[a,24] (* Stefano Spezia, Jun 14 2025 *)

PARI

forprime(p=2,1e3,print1((p^5-p^4)/2", ")) \\ Charles R Greathouse IV, Jul 15 2011

Formula

a(n) = A138407(n)/2. - R. J. Mathar, Oct 15 2017

Extensions

a(25)-a(28) from Stefano Spezia, Jun 14 2025