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%I #23 Oct 15 2019 11:47:41
%S 22,0,11,4,2,0,0,2,1,0,0,2,2,0,0,0,0,2,0,2,2,0,0,0,0,2,0,0,2,1,2,1,0,
%T 0,0,0,0,2,0,0,1,2,0,0,0,0,2,0,0,1,0,0,3,1,0,0,0,2,0,0,0,0,2,1,2,0,0,
%U 0,0,0,0,0,0,0,0,3,1,0,1,0,0,5,0,2,0,0,1,0,0,0
%N a(n) is exponential digital index of prime(n).
%C For the definition of the exponential digital index of a prime p (EDI(p)), see comment in A252668.
%C Is 22 the maximal term? Is 11 the second maximal term?
%F a(n)=0, iff n is not in A251964; a(n)=1, iff n is in A251964, but is not A252280;
%F a(n)=2, iff n is in A251964 & A252980, but is not in A252981, a(n)>=3, iff n is in A251964 & A252980 & A252281.
%o (PARI) s(k, pp) = my(sd = sumdigits(pp^k)); sd/2^valuation(sd, 2);
%o f(n, pp) = {my(p = prime(n), k = 1); while ((sk=s(k, pp)) % p, k++); if (sk == p, k, 0); }
%o a(n) = {my(pp=prime(n), j=3); while (f(j,pp), j++); j - 3;} \\ _Michel Marcus_, Dec 09 2018
%Y Cf. A000040, A251964, A252280, A252281, A252282, A252283, A252666, A252668.
%K nonn,base
%O 1,1
%A _Vladimir Shevelev_, Dec 20 2014
%E More terms from _Michel Marcus_, Dec 09 2018
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