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

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

(Magma) [n: n in [1..250] | IsPrime(1+SumOfDivisors(n)^4)]; // Vincenzo Librandi, Jun 24 2015
(PARI) is(n)=my(s=sigma(n)); isprime(s^4+1) \\ Charles R Greathouse IV, May 22 2017

Crossrefs

Cf. A000203, A259308, A259310.

Sequence in context: A361322 A037221 A182537 * A212061 A287570 A265220

Adjacent sequences: A259306 A259307 A259308 * A259310 A259311 A259312

Keyword

easy,nonn

Author

Robert Price, Jun 24 2015

Status

approved