A346991 Numbers occurring as divisors of 2^k + 5^k, k > 0.

1, 7, 11, 17, 19, 23, 29, 37, 41, 47, 49, 53, 59, 61, 73, 77, 89, 97, 101, 103, 109, 113, 121, 127, 131, 133, 137, 139, 149, 161, 167, 173, 179, 181, 193, 209, 211, 223, 229, 233, 241, 251, 253, 257, 259, 263, 269, 277, 281, 287, 289, 313, 317, 329, 331, 337, 343

Offset: 1

Author

Hugo Pfoertner, Aug 11 2021

Keywords

• nonn

Comments

If k is a term, then so are all divisors of k. - Robert Israel, Dec 08 2022

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A074600, A043292.

Programs

Maple

filter:= proc(n) local q, v;
   if igcd(n,10) <> 1 then return false fi;
   q:= 5/2 mod n;
   traperror(NumberTheory:-ModularLog(-1,q,n)) <> lasterror
end proc:
filter(1):= true:
select(filter, [$1..400]); # Robert Israel, Dec 08 2022