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A064234 The least k such that {A063994} Product_{primes p dividing k } gcd(p-1, k-1) = n, or 0 if impossible. 1
1, 3, 28, 5, 66, 7, 232, 45, 190, 11, 276, 13, 1106, 0, 286, 17, 1854, 19, 3820, 891, 2752, 23, 1128, 595, 2046, 0, 532, 29, 1770, 31, 9952, 425, 1288, 0, 2486, 37, 8474, 0, 742, 41, 3486, 43, 7612, 5589, 2356, 47, 13584, 325, 9850, 0, 20554, 53, 5778 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..53.

MATHEMATICA

f[ n_ ] := If[ n == 1, 1, Apply[ Times, GCD[ n - 1, Transpose[ FactorInteger[ n ] ] [ [ 1 ] ] - 1 ] ] ]; a = Table[ 0, {100} ]; Do[ m = f[ n ]; If[ m < 101 && a[ [ m ] ] == 0, a[ [ m ] ] = n ], {n, 1, 10^7} ]; a a(54) > 2*10^7. The zeros appear at positions that are the values in the sequence A005277, the nontotients: even n such that phi(m) = n has no solution.

CROSSREFS

Cf. A063994 and A005277.

Sequence in context: A162414 A188927 A146072 * A224579 A037102 A042169

Adjacent sequences:  A064231 A064232 A064233 * A064235 A064236 A064237

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Sep 22 2001

STATUS

approved

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Last modified November 17 01:58 EST 2018. Contains 317275 sequences. (Running on oeis4.)