OFFSET
1,1
COMMENTS
LINKS
Dumitru Damian, Table of n, a(n) for n = 1..30000
EXAMPLE
13 is in A336263, therefore 1 + 13 + 2*13*1 = 40 is a term, and (40*2) + 1 = 81 is not the product of 3 prime numbers.
MATHEMATICA
Select[Range[650], PrimeOmega[2*# + 1] >= 4 &] (* Amiram Eldar, Oct 24 2020 *)
PROG
(PARI) isok(k) = bigomega(2*k+1) >= 4; \\ Michel Marcus, Oct 24 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Davide Rotondo, Oct 23 2020
STATUS
approved