A259369 a(n) = 1 + sigma(n)^3 + sigma(n)^6.

3, 757, 4161, 117993, 46873, 2987713, 262657, 11394001, 4829007, 34018057, 2987713, 481912257, 7532281, 191116801, 191116801, 887533473, 34018057, 3518803081, 64008001, 5489105833, 1073774593, 2176828993, 191116801, 46656216001, 887533473, 5489105833

Offset: 1

Author

Robert Price, Jun 25 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), A060883 (n^6 + n^3 + 1).

Cf. A259370 (indices of primes in this sequence), A259371 (corresponding primes).

Programs

Magma

[1+SumOfDivisors(n)^3+ SumOfDivisors(n)^6: n in [1..50]]; // Vincenzo Librandi, Jun 26 2015

Maple

with(numtheory): A259369:=n->1+sigma(n)^3+sigma(n)^6: seq(A259369(n), n=1..40); # Wesley Ivan Hurt, Jun 29 2015

Mathematica

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

PARI

a(n) = polcyclo(9, sigma(n)) \\ Michel Marcus, Jun 25 2015

Formula

a(n) = 1 + A000203(n)^3 + A000203(n)^6.

a(n) = A060883(A000203(n)). - Michel Marcus, Jun 25 2015