A063451 Numbers k such that k*sigma(k) - 1 is a prime.

2, 3, 5, 6, 10, 11, 13, 15, 18, 19, 20, 24, 26, 28, 31, 33, 41, 50, 51, 53, 56, 59, 60, 63, 70, 76, 78, 80, 82, 83, 86, 89, 90, 93, 95, 99, 101, 102, 103, 104, 111, 116, 122, 123, 131, 132, 142, 143, 144, 145, 146, 148, 149, 150, 152, 153, 154, 155, 156, 161, 163

Offset

1,1

Links

Harry J. Smith, Table of n, a(n) for n = 1..1000

Prog

(PARI) j=[]; for(n=1, 350, if(isprime(n*sigma(n)-1), j=concat(j, n))); j
(PARI)  n=0; for (m=1, 10^9, if (isprime(m*sigma(m) - 1), write("b063451.txt", n++, " ", m); if (n==1000, break)))  \\ Harry J. Smith, Aug 21 2009

Crossrefs

Sequence in context: A094739 A302494 A302534 * A276625 A297571 A316503

Adjacent sequences: A063448 A063449 A063450 * A063452 A063453 A063454

Keyword

easy,nonn

Author

Jason Earls, Jul 25 2001

Status

approved