OFFSET
1,1
COMMENTS
All the terms of the form 4u+2 in A349745 (if they exist) are found in this sequence. As A351537 is the intersection of A191218 and A329963, and the latter has asymptotic density zero, so has this sequence also. It is conjectured that A351555(a(n)) is nonzero for all n, which would imply that the intersection with A349745 is empty. - Antti Karttunen, Feb 19 2022
LINKS
FORMULA
a(n) = 2 * A351537(n).
PROG
(PARI) isA351538(n) = if(!(2==(n%4)), 0, my(s=sigma(n)); (2 == (s%4)) && (1==valuation(s, 3)));
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Feb 14 2022
STATUS
approved