A258978 -id:A258978 - cp's OEIS frontend

A258980 Primes in A258978.

5, 2801, 22621, 30941, 22621, 637421, 346201, 346201, 346201, 2625641, 837931, 16007041, 3835261, 209102521, 209102521, 15018571, 262209281, 21700501, 30397351, 209102521, 209102521, 693025471, 147753211, 4244897281, 1740422941, 6903678241, 2439903211

Offset: 1

Robert Price, Jun 15 2015

nonn

These primes are neither sorted nor uniqued. They are listed in the order found in A258978.

Robert Price, Table of n, a(n) for n = 1..932
OEIS Wiki, Cyclotomic Polynomials at x=n, n! and sigma(n)

Cf. A000203, A258978, A258979.

[m: n in [1..200] | IsPrime(m) where m is (1 + DivisorSigma(1, n) + DivisorSigma(1, n)^2 + DivisorSigma(1, n)^3 + DivisorSigma(1, n)^4)]; // Vincenzo Librandi, Jun 16 2015

with(numtheory): A258980:=n->`if`(isprime(1 + sigma(n) + sigma(n)^2 + sigma(n)^3 + sigma(n)^4), 1 + sigma(n) + sigma(n)^2 + sigma(n)^3 + sigma(n)^4, NULL): seq(A258980(n), n=1..300); # Wesley Ivan Hurt, Jul 09 2015

Select[Table[1 + DivisorSigma[1, n] + DivisorSigma[1, n]^2 + DivisorSigma[1, n]^3 + DivisorSigma[1, n]^4, {n, 10000}], PrimeQ]
Select[Table[Cyclotomic[5, DivisorSigma[1, n]], {n, 10000}], PrimeQ]

a(n) = A258978(A258979(n)).

A258979 Numbers n such that 1 + sigma(n) + sigma(n)^2 + sigma(n)^3 + sigma(n)^4 is prime.

Original entry on oeis.org

1, 4, 6, 9, 11, 12, 14, 15, 23, 27, 29, 32, 43, 54, 56, 61, 64, 67, 73, 87, 95, 106, 109, 128, 134, 138, 146, 154, 163, 165, 171, 172, 197, 213, 235, 252, 253, 258, 259, 273, 274, 290, 300, 301, 303, 307, 314, 326, 330, 335, 358, 387, 393, 394, 403, 404, 412

Offset: 1

Robert Price, Jun 15 2015

nonn

Robert Price, Table of n, a(n) for n = 1..932
OEIS Wiki, Cyclotomic Polynomials at x=n, n! and sigma(n)

Cf. A000203, A258978, A258980.

[n: n in [1..500] | IsPrime(1 + DivisorSigma(1, n) + DivisorSigma(1, n)^2 + DivisorSigma(1, n)^3 + DivisorSigma(1, n)^4)]; // Vincenzo Librandi, Jun 16 2015

with(numtheory): A258979:=n->`if`(isprime(1 + sigma(n) + sigma(n)^2 + sigma(n)^3 + sigma(n)^4), n, NULL): seq(A258979(n), n=1..1000); # Wesley Ivan Hurt, Jul 09 2015

Select[ Range[10000], PrimeQ[ 1 + DivisorSigma[1, #] + DivisorSigma[1, #]^2 + DivisorSigma[1, #]^3 + DivisorSigma[1, #]^4] & ]
Select[ Range[10000], PrimeQ[ Cyclotomic[5, DivisorSigma[1, #]]] &]
Select[Range[10000],PrimeQ[Total[DivisorSigma[1,#]^Range[0,4]]]&] (* Harvey P. Dale, Aug 17 2015 *)

is(n)=my(s=sigma(n)); isprime(s^4+s^3+s^2+s+1) \\ Charles R Greathouse IV, May 22 2017

cp's OEIS Frontend

A258980 Primes in A258978.

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