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
Keywords
Examples
a(1)=6803 because 6797=7*971, 6799=13*523, 6801=3*2267, 6805=5*1361, 6807=3*2269, 6809=11*619.
Links
- Zak Seidov, Table of n, a(n) for n = 1..3000
Programs
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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
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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
Extensions
More terms from Michel Marcus, Jan 07 2016