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%I #10 Oct 25 2019 12:28:12
%S 0,3,2,1,2,7,4,4,4,4,8,7,5,15,4,7,5,9,15,3,5,8,16,19,20,17,9,12,18,6,
%T 26,8,29,8,11,19,29,35,19,40,22,41,40,5
%N a(n) is the only number m such that 10^(2^m) + 1 is divisible by A072982(n+1).
%F a(n) = A197224(n+1) - 1. - _Ray Chandler_, Oct 25 2019
%o (PARI) forstep(p=3, 10^15, 2, if(!Mod(p, 5)==0, if(isprime(p), o=znorder(Mod(10, p)); x=ispower(2*o); if(2^(x-1)==o, print1(x-2, ", ")))));
%Y Cf. A072982, A197224.
%K nonn,more
%O 1,2
%A _Arkadiusz Wesolowski_, Jun 25 2016
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