OFFSET
1,1
COMMENTS
If an even number has exactly 6 divisors, then it is of the form 32, 4*p or 2*p^2 for an odd prime p. Note that 4*p + 2 = 2*q^2 is impossible since q^2 - 1 is divisible by 24 for prime q >= 5. As a result, if k is an even term, then it is of the form 2*p^2 such that (p^2+1)/2 is a prime (p is in A048161).
LINKS
Jianing Song, Table of n, a(n) for n = 1..10000
EXAMPLE
50 is a term since 50 and 52 both have 6 divisors.
PROG
(PARI) isA356743(n) = numdiv(n)==6 && numdiv(n+2)==6
CROSSREFS
KEYWORD
nonn
AUTHOR
Jianing Song, Aug 25 2022
STATUS
approved