A258977 Primes in A258974.

2, 17, 37, 197, 577, 577, 401, 1297, 577, 1601, 3137, 2917, 3137, 8101, 7057, 15377, 2917, 14401, 14401, 8101, 7057, 15877, 5477, 15377, 15877, 7057, 50177, 14401, 32401, 8101, 14401, 24337, 44101, 78401, 12101, 57601, 44101, 32401, 50177, 24337, 30977

Offset

1,1

Comments

These primes are neither sorted nor uniqued. They are listed in the order found in A258974.

Links

Robert Price, Table of n, a(n) for n = 1..1786

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

Formula

a(n) = A258974(A258976(n)).

Maple

with(numtheory): A258977:=n->`if`(isprime(1+sigma(n)^2), 1+sigma(n)^2, NULL): seq(A258977(n), n=1..300); # Wesley Ivan Hurt, Jul 09 2015

Mathematica

Select[Table[1 + DivisorSigma[1, n]^2, {n, 10000}], PrimeQ]
Select[Table[Cyclotomic[4, DivisorSigma[1, n]], {n, 10000}], PrimeQ]

Prog

(Magma) [m: n in [1..200] | IsPrime(m) where m is 1 + DivisorSigma(1, n)^2]; // Vincenzo Librandi, Jun 16 2015
(PARI) for(n=1, 100, p=1+sigma(n)^2; if(isprime(p), print1(p, ", "))) \\ Derek Orr, Jun 18 2015

Crossrefs

Cf. A000203, A258974, A258976.

Sequence in context: A095075 A307161 A294560 * A069042 A121923 A212276

Adjacent sequences: A258974 A258975 A258976 * A258978 A258979 A258980

Keyword

nonn

Author

Robert Price, Jun 15 2015

Status

approved