A115093 Primes of the form p*q-2, where p and q are distinct primes.

13, 19, 31, 37, 53, 67, 83, 89, 109, 113, 127, 131, 139, 157, 181, 199, 211, 233, 251, 257, 263, 293, 307, 317, 337, 353, 379, 389, 401, 409, 443, 449, 467, 479, 487, 491, 499, 503, 509, 541, 557, 563, 571, 577, 587, 631, 647, 653, 677, 683, 701, 719, 743

Offset

1,1

Comments

This sequence is a subset of A063637, which is the union of this sequence and A049002.

Links

Table of n, a(n) for n=1..53.

Mathematica

SemiPrimeQ[n_] := (n>1) && (2==Plus@@(Transpose[FactorInteger[n]][[2]])); Select[Prime[Range[150]], SemiPrimeQ[ #+2] && !IntegerQ[Sqrt[ #+2]]&]

Crossrefs

Cf. A049002 (primes of the form p^2-2, where p is prime), A063637 (primes of the form p*q-2 where p and q are primes).

Sequence in context: A307533 A092738 A272382 * A158195 A040092 A079130

Adjacent sequences: A115090 A115091 A115092 * A115094 A115095 A115096

Keyword

nonn

Author

T. D. Noe, Mar 01 2006

Status

approved