A259310 Primes of the form: 1 + sigma(n)^4.

2, 257, 1297, 614657, 331777, 331777, 160001, 331777, 9834497, 5308417, 8503057, 5308417, 9834497, 65610001, 5308417, 8503057, 40960001, 65610001, 29986577, 384160001, 40960001, 303595777, 1049760001, 65610001, 1944810001, 3782742017, 1944810001, 1049760001

Offset: 1

Author

Robert Price, Jun 24 2015

Keywords

• easy
• nonn

Comments

These primes are neither sorted nor uniqued. They are listed in the order found in A259308.

Links

• Robert Price, Table of n, a(n) for n = 1..1459
• OEIS Wiki, Cyclotomic Polynomials at x=n, n! and sigma(n)

Crossrefs

Cf. A000203, A259308, A259309.

Programs

Magma

[a: n in [1..150] | IsPrime(a) where a is 1 + SumOfDivisors(n)^4]; // Vincenzo Librandi, Jun 24 2015

Maple

with(numtheory): A259310:=n->`if`(isprime(1+sigma(n)^4), 1+sigma(n)^4, NULL): seq(A259310(n), n=1..200); # Wesley Ivan Hurt, Jul 09 2015

Mathematica

Select[Table[1 + DivisorSigma[1, n]^4, {n, 10000}], PrimeQ]
Select[Table[Cyclotomic[8, DivisorSigma[1, n]], {n, 10000}], PrimeQ]

Formula

a(n) = A259308(A259309(n)).