Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #16 Dec 10 2022 10:47:01
%S 1,5,7,11,13,17,25,31,35,37,41,49,55,59,61,73,77,79,83,89,97,103,107,
%T 109,113,121,125,127,131,137,149,151,155,157,169,173,175,179,181,193,
%U 199,217,223,227,229,233,241,245,251,257,271,275,277,281,289,295,313
%N Numbers occurring as divisors of 2^k + 3^k, k > 0.
%C If n is a term, then so are all divisors of n. - _Robert Israel_, Dec 08 2022
%H Robert Israel, <a href="/A346990/b346990.txt">Table of n, a(n) for n = 1..10000</a>
%p filter:= proc(n) local v;
%p if igcd(n,6) <> 1 then return false fi;
%p q:= 3/2 mod n;
%p traperror(NumberTheory:-ModularLog(-1,q,n)) <> lasterror
%p end proc:
%p filter(1):= true:
%p select(filter, [$1..400]); # _Robert Israel_, Dec 08 2022
%Y Cf. A007689, A005056.
%K nonn
%O 1,2
%A _Hugo Pfoertner_, Aug 11 2021