A202607 Numbers n such that 6n and sigma(6n) are both a twin prime average.

1, 5, 77, 177, 215, 247, 313, 348, 465, 593, 712, 723, 1092, 1110, 1218, 1335, 1433, 1470, 1673, 1738, 1755, 1815, 1990, 2007, 2153, 2223, 2293, 2830, 2903, 2930, 3042, 3332, 3598, 3673, 3790, 3957, 4308, 4477, 4623, 5338, 5548, 5955, 6258, 6297, 7030, 7095

Offset

1,2

Links

Table of n, a(n) for n=1..46.

Example

a(4)=177 because 6*177-1=1061, 6*177+1=1063, A000203(6*177)-1=2339 and A000203(6*177)+1=2341 are all primes.

Prog

(PARI) for(n=1, 1e4, if(isprime(6*n-1)&&isprime(6*n+1)&&isprime(sigma(6*n)-1)&&isprime(sigma(6*n)+1), print1(n", "))) \\ Charles R Greathouse IV, Dec 26 2011

Crossrefs

Cf. A000203, A014574, A193687.

Sequence in context: A088756 A319186 A076215 * A222533 A059856 A001513

Adjacent sequences: A202604 A202605 A202606 * A202608 A202609 A202610

Keyword

nonn,less

Author

Juri-Stepan Gerasimov, Dec 21 2011

Status

approved