A331858 a(n) = (2^p-1)*(2^(p-1))*((2^p-1)^2-2), where p is the n-th prime.

42, 1316, 475664, 131080256, 8783210218496, 2250975213522944, 147570574898545885184, 37778715690312487141376, 2475879193127080196116054016, 41538374636164863806350357434466304, 10633823951424046514111736193740701696, 178405961584350762488394070192754827810832384

Offset: 1

Author

G. L. Honaker, Jr., Jan 29 2020

Keywords

• nonn
• easy

Comments

Integers a(1), a(2), a(4), a(8) corresponding to p = 2, 3, 7, 19 are also terms of A331805. - Bernard Schott, Feb 04 2020

Crossrefs

Cf. A000040 (primes), A000396 (perfect numbers), A093112 ((2^n-1)^2-2), A060286 (2^(p-1)*(2^p-1)), A331805.

Programs

Mathematica

f[p_] := (2^p-1)*(2^(p-1))*((2^p-1)^2-2); f @ Prime @ Range[12] (* Amiram Eldar, Jan 29 2020 *)

PARI

[(2^p-1)*((2^p-1)^2-2)<<(p-1) | p<-primes(12)] \\ or: a(n,p=prime(n))={...}. - M. F. Hasler, Jan 29 2020

Formula

a(n) = A060286(n)*A093112(prime(n)). - M. F. Hasler, Jan 31 2020