A274508 - OEIS

%I #10 Jul 06 2016 00:55:26

%S 1,3,2,3,7,8,10,15,7,15,11,8,19,4,9,21,10,11,10,26,28,9,29,32,31,38,9,

%T 39,34,21,7,31,26,36,5

%N a(n) is the only number m such that 3^(2^m) + 1 is divisible by A273945(n).

%o (PARI) forstep(p=3, 10^15, 2, if(!Mod(p, 3)==0, if(isprime(p), o=znorder(Mod(3, p)); x=ispower(2*o); if(2^(x-1)==o, print1(x-2, ", ")))));

%Y Cf. A273945.

%K nonn,more

%O 1,2

%A _Arkadiusz Wesolowski_, Jun 25 2016