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A319313 a(n) is the least integer m such that A047994(m) = ((n-2)/n)*m where A047994 is the unitary totient function, or 0 if there is no such m. 0
6, 2, 20, 3, 1008, 4, 72, 5, 4400, 144, 835660800, 7, 10800, 8, 272, 9, 9849600, 400, 208039104, 11, 145520912351232000000, 64281600, 3608344625286776094720000, 13, 1296, 84672, 90944, 129600 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,1

LINKS

Table of n, a(n) for n=3..30.

Yasutoshi Kohmoto, UnitaryPhi, SeqFan list, Aug-Sep 2018.

FORMULA

a(2n) = A318842(n).

PROG

(PARI) \\ uses the "solve_uphi pari code", see A318842 links

a(n) = {my(lim = 1, v); while (1, v = solve_uphi(n-2, n, lim); if (#v, return (v[1])); lim *= 10; ); }

CROSSREFS

Cf. A047994 (unitary totient).

Cf. A030163, A305678, A318842.

Sequence in context: A248269 A081778 A055943 * A277275 A213503 A169632

Adjacent sequences:  A319310 A319311 A319312 * A319314 A319315 A319316

KEYWORD

nonn,more

AUTHOR

Michel Marcus, Sep 17 2018

STATUS

approved

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Last modified April 3 21:07 EDT 2020. Contains 333205 sequences. (Running on oeis4.)