A070957 Primes p such that the equation sigma(x) = p has no solution.

2, 5, 11, 17, 19, 23, 29, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Mathematica

r = Range[300]; Complement[Select[r, PrimeQ], DivisorSigma[1, r]] (* Amiram Eldar, Nov 15 2021 *)

Prog

(PARI) for(n=1, 100, if(sum(j=1, n, if(sigma(j)-n, 1-isprime(n), 1))==0, print1(n, ", ")))

Crossrefs

The prime terms in A007369.

Sequence in context: A118660 A009770 A132121 * A166744 A080165 A239712

Adjacent sequences: A070954 A070955 A070956 * A070958 A070959 A070960

Keyword

easy,nonn

Author

Benoit Cloitre, May 16 2002

Status

approved