A193144 Primes of the form n^2 + n + 1, where n is semiprime.

43, 211, 241, 463, 1123, 1483, 3307, 3907, 4831, 6007, 12433, 14281, 20023, 20593, 24181, 26083, 37831, 41413, 42643, 43891, 46441, 47743, 77563, 82657, 95791, 98911, 108571, 145543, 156421, 158803, 200257, 205663, 239611, 284623, 288907, 304153, 307471

Offset

1,1

Comments

This is to semiprimes A001358 as A185632 is to nonprimes A018252.

Links

Table of n, a(n) for n=1..37.

Formula

{k: k is in A001358 and n^2 + n + 1 is in A000040}.

Example

43 is in the sequence because it is prime, and 43 = 6^2 + 6 + 1 where 6 = 2*3 is semiprime.

Mathematica

Select[#^2+#+1&/@Select[Range[1000], PrimeOmega[#]==2&], PrimeQ] (* Harvey P. Dale, Jan 06 2013 *)

Crossrefs

Cf. A000040, A001358, A185632, A192321.

Sequence in context: A145650 A142527 A142161 * A142659 A140041 A264821

Adjacent sequences: A193141 A193142 A193143 * A193145 A193146 A193147

Keyword

nonn,easy

Author

Jonathan Vos Post, Dec 19 2012

Status

approved