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A252670
a(n) is exponential digital index of prime(n).
1
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, 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, 0, 0, 0, 0, 0, 0, 0, 0, 3, 1, 0, 1, 0, 0, 5, 0, 2, 0, 0, 1, 0, 0, 0
OFFSET
1,1
COMMENTS
For the definition of the exponential digital index of a prime p (EDI(p)), see comment in A252668.
Is 22 the maximal term? Is 11 the second maximal term?
FORMULA
a(n)=0, iff n is not in A251964; a(n)=1, iff n is in A251964, but is not A252280;
a(n)=2, iff n is in A251964 & A252980, but is not in A252981, a(n)>=3, iff n is in A251964 & A252980 & A252281.
PROG
(PARI) s(k, pp) = my(sd = sumdigits(pp^k)); sd/2^valuation(sd, 2);
f(n, pp) = {my(p = prime(n), k = 1); while ((sk=s(k, pp)) % p, k++); if (sk == p, k, 0); }
a(n) = {my(pp=prime(n), j=3); while (f(j, pp), j++); j - 3; } \\ Michel Marcus, Dec 09 2018
KEYWORD
nonn,base
AUTHOR
Vladimir Shevelev, Dec 20 2014
EXTENSIONS
More terms from Michel Marcus, Dec 09 2018
STATUS
approved