A266847 Primes p such that p+/-2, p+/-4 and p+/-6 are semiprimes.

6803, 52163, 67103, 116009, 155609, 196613, 242243, 277703, 523403, 706987, 764189, 973853, 1053863, 1307197, 1610333, 1823797, 1843687, 1995337, 2186603, 2487367, 2638747, 2875643, 2972663, 3032693, 3137399, 3179107, 3203243, 3209797, 3393809, 3454201, 3548033, 4302847, 4523093

Offset

1,1

Links

Zak Seidov, Table of n, a(n) for n = 1..3000

Example

a(1)=6803 because  6797=7*971, 6799=13*523, 6801=3*2267, 6805=5*1361, 6807=3*2269, 6809=11*619.

Prog

(PARI) lista(nn) = {forprime(p=7, nn, if (bigomega(p-6)==2 && bigomega(p+6)==2 && bigomega(p-4)==2 && bigomega(p+4)==2 && bigomega(p-2)==2 && bigomega(p+2)==2, print1(p, ", ")); ); } \\ Michel Marcus, Jan 07 2016
(Magma) IsSemiprime:=func< p | &+[ k[2]: k in Factorization(p)] eq 2 >; [p: p  in PrimesInInterval(3, 4*10^6)| IsSemiprime(p+2) and IsSemiprime(p-2) and IsSemiprime(p+4) and IsSemiprime(p-4)and IsSemiprime(p+6) and IsSemiprime(p-6)]; // Vincenzo Librandi, Jan 07 2016

Crossrefs

Subsequence of A266845 and A063643.

Sequence in context: A121106 A046515 A199996 * A345592 A345850 A132215

Adjacent sequences: A266844 A266845 A266846 * A266848 A266849 A266850

Keyword

nonn

Author

Zak Seidov, Jan 04 2016

Extensions

More terms from Michel Marcus, Jan 07 2016

Status

approved