A259309 - OEIS

A259309

Numbers n such that 1 + sigma(n)^4 is prime.

1, 3, 5, 12, 14, 15, 19, 23, 28, 33, 34, 35, 39, 40, 47, 53, 57, 58, 73, 76, 79, 86, 88, 89, 104, 112, 116, 118, 126, 131, 133, 134, 138, 139, 145, 147, 148, 154, 163, 165, 173, 175, 179, 183, 185, 189, 193, 197, 201, 204, 206, 207, 213, 216, 219, 220, 224

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OFFSET

1,2

LINKS

Robert Price, Table of n, a(n) for n = 1..1459

OEIS Wiki, Cyclotomic Polynomials at x=n, n! and sigma(n)

MAPLE

with(numtheory): A259309:=n->`if`(isprime(1 + sigma(n)^4), n, NULL): seq(A259309(n), n=1..500); # Wesley Ivan Hurt, Jul 09 2015

MATHEMATICA

Select[ Range[10000], PrimeQ[ 1 + DivisorSigma[1, #]^4] & ]

Select[ Range[10000], PrimeQ[ Cyclotomic[8, DivisorSigma[1, #]]] &]

PROG