A079449 Primes p such that there is at least one integer x satisfying p=x*tau(x)+1 where tau(x)=A000005(x), the number of divisors of x.

2, 5, 7, 11, 13, 23, 41, 47, 59, 61, 73, 83, 89, 107, 109, 137, 157, 167, 179, 193, 227, 229, 233, 241, 263, 271, 277, 313, 337, 347, 349, 359, 373, 379, 383, 409, 433, 449, 457, 461, 467, 479, 503, 563, 569, 587, 709, 719, 733, 809, 821, 839, 853, 857, 863

Offset

1,1

Links

Table of n, a(n) for n=1..55.

Example

12*tau(12)=72 hence 73 is in the sequence.

Prog

(PARI) lista(nn) = {forprime(p=2, nn, for (n=1, p, if (n*numdiv(n)+1 == p, print1(p, ", "); break; ); ); ); } \\ Michel Marcus, Dec 01 2013

Crossrefs

Cf. A079448.

Sequence in context: A291280 A120330 A023216 * A236071 A038885 A302988

Adjacent sequences: A079446 A079447 A079448 * A079450 A079451 A079452

Keyword

nonn

Author

Benoit Cloitre, Jan 13 2003

Status

approved