A133395 Terms in A061725 that are of form 3*prime.

6, 51, 123, 291, 843, 1371, 1851, 2811, 5331, 6243, 6891, 9411, 18771, 36483, 54291, 63003, 69171, 72363, 73443, 76731, 78963, 128883, 143643, 151323, 187491, 212523, 229443, 271443, 292683, 332931, 361203, 398163, 418611, 458331, 477483, 516963

Offset: 1

Author

Zak Seidov, Dec 22 2007

Keywords

• nonn

Comments

3|p^2+2 for all p except 3 hence 3|A061725(n) for all n except n=2. If p^2+2 is semiprime it is of form 3*prime.

Crossrefs

Cf. A061725 (p^2+2 where p=prime).

Programs

PARI

lista(nn) = {vec = vector(nn, i, prime(i)^2 + 2); pp = select(i->((bigomega(i) == 2) && !(i % 3)), vec); print(pp);} \\ Michel Marcus, Oct 13 2013

Extensions

Typo in Comment corrected by Shai Covo (green355(AT)netvision.net.il), Oct 11 2010