A068419 Odd prime values of sigma(k) - phi(k) taking k in increasing order.

5, 11, 7, 23, 11, 47, 79, 73, 67, 23, 191, 283, 383, 739, 47, 1459, 281, 607, 59, 1153, 1069, 3319, 83, 1801, 2671, 3517, 743, 107, 6679, 3529, 6619, 6143, 6271, 4153, 10169, 9817, 167, 6451, 179, 24097, 23539, 10369, 227, 263, 16369, 41203, 20809, 54919

Offset

1,1

Links

Table of n, a(n) for n=1..48.

Example

sigma(2312) - phi(2312) = 3517 is prime, so is in the sequence.

Prog

(PARI) lista(nn) = {for (k = 1, nn, if (isprime(p = (sigma(k) - eulerphi(k))) && (p % 2), print1(p, ", ")); ); } \\ Michel Marcus, Nov 24 2013

Crossrefs

Cf. A051612.

Sequence in context: A226606 A226619 A367705 * A226586 A368055 A358613

Adjacent sequences: A068416 A068417 A068418 * A068420 A068421 A068422

Keyword

easy,nonn

Author

Benoit Cloitre, Mar 02 2002

Extensions

Terms 3517, 10169, 9817 added by Michel Marcus, Nov 24 2013

Status

approved