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

1,1

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)

Formula

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

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]

Prog

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

Crossrefs

Cf. A000203, A259308, A259309.

Sequence in context: A240551 A078168 A003380 * A060890 A294275 A085316

Adjacent sequences: A259307 A259308 A259309 * A259311 A259312 A259313

Keyword

easy,nonn

Author

_Robert Price_, Jun 24 2015

Status

approved