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A025476 Prime root of n-th nontrivial prime power (A025475). 4
2, 2, 3, 2, 5, 3, 2, 7, 2, 3, 11, 5, 2, 13, 3, 2, 17, 7, 19, 2, 23, 5, 3, 29, 31, 2, 11, 37, 41, 43, 2, 3, 13, 47, 7, 53, 5, 59, 61, 2, 67, 17, 71, 73, 79, 3, 19, 83, 89, 2, 97, 101, 103, 107, 109, 23, 113, 11, 5, 127, 2, 7, 131, 137, 139, 3, 149, 151, 29, 157, 163, 167, 13, 31, 173, 179 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..76.

MAPLE

cvm := proc(n, level) local f, opf; if n < 2 then RETURN() fi;

f := ifactors(n); opf := op(1, op(2, f)); if nops(op(2, f)) > 1 or

op(2, opf) <= level then RETURN() fi; op(1, opf) end:

A025476_list := n -> seq(cvm(i, 1), i=1..n); # n is search limit

A025476_list(30000);  # Peter Luschny, Sep 21 2011

MATHEMATICA

Transpose[ Flatten[ FactorInteger[ Select[ Range[2, 30000], !PrimeQ[ # ] && Mod[ #, # - EulerPhi[ # ]] == 0 &]], 1]][[1]] (* Robert G. Wilson v *)

PROG

(PARI) forcomposite(n=4, 10^5, if( ispower(n, , &p) && isprime(p), print1(p, ", "))) \\ Joerg Arndt, Sep 11 2021

CROSSREFS

Cf. A025473, A025475, A048148.

Sequence in context: A157987 A025478 A084371 * A347731 A331532 A078773

Adjacent sequences:  A025473 A025474 A025475 * A025477 A025478 A025479

KEYWORD

easy,nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified August 18 12:46 EDT 2022. Contains 356212 sequences. (Running on oeis4.)