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A252670
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a(n) is exponential digital index of prime(n).
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1
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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
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OFFSET
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1,1
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COMMENTS
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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?
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LINKS
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Table of n, a(n) for n=1..90.
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FORMULA
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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.
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PROG
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(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
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CROSSREFS
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Cf. A000040, A251964, A252280, A252281, A252282, A252283, A252666, A252668.
Sequence in context: A023922 A022064 A225343 * A297813 A156462 A040488
Adjacent sequences: A252667 A252668 A252669 * A252671 A252672 A252673
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KEYWORD
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nonn,base
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AUTHOR
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Vladimir Shevelev, Dec 20 2014
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EXTENSIONS
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More terms from Michel Marcus, Dec 09 2018
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STATUS
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approved
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