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

1,1

Comments

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

Links

Table of n, a(n) for n=1..38.

Example

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

Prog

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

Crossrefs

Cf. A000040, A001358, A014612, A234095.

Sequence in context: A194784 A184153 A184145 * A008388 A241939 A251896

Adjacent sequences: A238199 A238200 A238201 * A238203 A238204 A238205

Keyword

nonn

Author

Zak Seidov, Feb 20 2014

Status

approved