A259371 Primes of the form 1 + sigma(n)^3 + sigma(n)^6.

3, 757, 262657, 64008001, 46656216001, 30841155073, 729027001, 46656216001, 30841155073, 225200075257, 885843322057, 46656216001, 41407378175593, 885843322057, 25002115044733, 1126163480473, 85766130261001, 191102989824001, 85766130261001, 41407378175593

Offset: 1

Author

Robert Price, Jun 25 2015

Keywords

• easy
• nonn

Comments

These primes are neither sorted nor uniqued. They are listed in the order found in A259369.

Links

• Robert Price, Table of n, a(n) for n = 1..756
• OEIS Wiki, Cyclotomic Polynomials at x=n, n! and sigma(n)

Crossrefs

Cf. A000203, A259369, A259370.

Programs

Magma

[a: n in [1..150] | IsPrime(a) where a is 1 + SumOfDivisors(n)^3 + SumOfDivisors(n)^6]; // Vincenzo Librandi, Jun 26 2015

Maple

with(numtheory): b:=n->1+sigma(n)^3+sigma(n)^6: A259371:=n->`if`( isprime(b(n)), b(n), NULL): seq(A259371(n), n=1..200); # Wesley Ivan Hurt, Jun 29 2015

Mathematica

Select[Table[1 + DivisorSigma[1, n]^3 + DivisorSigma[1, n]^6, {n, 10000}], PrimeQ]
Select[Table[Cyclotomic[9, DivisorSigma[1, n]], {n, 10000}], PrimeQ]

Formula

a(n) = A259369(A259370(n)).