OFFSET
1,1
LINKS
Robert Price, Table of n, a(n) for n = 1..1017
MAPLE
with(numtheory): A259411:=n->`if`(isprime(1-sigma(n)+sigma(n)^2-sigma(n)^3+sigma(n)^4), n, NULL): seq(A259411(n), n=1..1000); # Wesley Ivan Hurt, Jul 09 2015
MATHEMATICA
Select[ Range[10000], PrimeQ[ 1 - DivisorSigma[1, #] + DivisorSigma[1, #]^2 - DivisorSigma[1, #]^3 + DivisorSigma[1, #]^4] & ]
Select[ Range[10000], PrimeQ[ Cyclotomic[10, DivisorSigma[1, #]]] &]
PROG
(Magma) [n: n in [1..600] | IsPrime(1 - DivisorSigma(1, n) + DivisorSigma(1, n)^2 - DivisorSigma(1, n)^3 + DivisorSigma(1, n)^4)]; // Vincenzo Librandi, Jun 27 2015
(PARI) is(n)=my(s=sigma(n)); isprime(s^4-s^3+s^2-s+1) \\ Charles R Greathouse IV, May 22 2017
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Robert Price, Jun 26 2015
STATUS
approved