A238202 Primes p such that b = 2*p + 1 is semiprime and c = 2*b + 1 is 3-almost prime.

43, 503, 631, 827, 971, 1063, 1153, 1283, 1373, 1429, 1433, 1493, 1523, 1553, 1619, 1693, 1877, 2113, 2239, 2243, 2297, 2423, 2477, 2531, 2609, 2683, 2851, 2927, 2999, 3203, 3221, 3319, 3463, 3533, 3557, 3571, 3583, 3701

Offset: 1

Author

Zak Seidov, Feb 20 2014

Keywords

• nonn

Comments

Subsequence of A234095 and A000040, e.g., a(1) = 43 = A234095(4) = A000040(14).

Examples

			2*43 + 1 = 87 = 2*29 = A001358(30), 2*87 + 1 = 175 = 5*5*7 = A014612(43).
		

Crossrefs

Cf. A000040, A001358, A014612, A234095.

Programs

PARI

forprime(p=2,4000,if(bigomega(a=2*p+1)==2&&bigomega(b=2*a+1)==3,print(p",")))