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

Author

Juri-Stepan Gerasimov, Dec 21 2011

Keywords

• nonn
• less

Examples

			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.
		

Crossrefs

Cf. A000203, A014574, A193687.

Programs

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