login
A202607
Numbers n such that 6n and sigma(6n) are both a twin prime average.
1
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
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
KEYWORD
nonn,less
AUTHOR
STATUS
approved