A337185 Composite numbers k such that A337183(k) is prime.

6, 10, 15, 21, 22, 26, 28, 33, 35, 38, 39, 42, 44, 45, 46, 50, 54, 62, 65, 66, 68, 69, 75, 76, 77, 82, 85, 95, 98, 99, 102, 105, 106, 111, 115, 116, 117, 118, 120, 123, 124, 126, 129, 132, 135, 141, 143, 145, 146, 152, 155, 158, 161, 168, 170, 176, 178, 186, 188, 198, 200, 201, 202, 203, 205, 206

Offset: 1

Author

J. M. Bergot and Robert Israel, Jan 29 2021

Keywords

• nonn
• base

Examples

			15 is a term because it is not prime and A337183(15) = 29 is prime.
		

Links

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

Crossrefs

Cf. A337183. Disjoint from A001597. Includes 2*k for k in A023209.

Programs

Maple

f:= proc(n) local F, b, i;
  F:= sort(map(t -> t[1]$t[2], ifactors(n)[2]), `>`);
  b:= convert(F, `+`);
  (add(F[i]*b^(i-1), i=1..nops(F)));
end proc:
select(t -> not isprime(t) and isprime(f(t)), [$2..300]);