A259308 a(n) = 1 + sigma(n)^4.

2, 82, 257, 2402, 1297, 20737, 4097, 50626, 28562, 104977, 20737, 614657, 38417, 331777, 331777, 923522, 104977, 2313442, 160001, 3111697, 1048577, 1679617, 331777, 12960001, 923522, 3111697, 2560001, 9834497, 810001, 26873857, 1048577, 15752962, 5308417

Offset: 1

Author

Robert Price, Jun 24 2015

Keywords

• easy
• nonn

Links

• Robert Price, Table of n, a(n) for n = 1..10000
• OEIS Wiki, Cyclotomic Polynomials at x=n, n! and sigma(n)

Crossrefs

Cf. A000203 (sum of divisors of n).

Cf. A259309 (indices of primes in this sequence), A259310 (corresponding primes).

Programs

Magma

[(1 + SumOfDivisors(n)^4): n in [1..50]]; // Vincenzo Librandi, Jun 24 2015

Maple

with(numtheory): A259308:=n->1+sigma(n)^4: seq(A259308(n), n=1..50); # Wesley Ivan Hurt, Jul 09 2015

Mathematica

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

Formula

a(n) = 1 + A000203(n)^4.

a(n) = A019326(A000203(n)). - Michel Marcus, Jun 24 2015