A046144 - OEIS

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A046144

Number of primitive roots of n.

1, 1, 1, 1, 2, 1, 2, 0, 2, 2, 4, 0, 4, 2, 0, 0, 8, 2, 6, 0, 0, 4, 10, 0, 8, 4, 6, 0, 12, 0, 8, 0, 0, 8, 0, 0, 12, 6, 0, 0, 16, 0, 12, 0, 0, 10, 22, 0, 12, 8, 0, 0, 24, 6, 0, 0, 0, 12, 28, 0, 16, 8, 0, 0, 0, 0, 20, 0, 0, 0, 24, 0, 24, 12, 0, 0, 0, 0, 24, 0, 18, 16, 40, 0, 0, 12, 0, 0, 40, 0, 0 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,5`
	LINKS	`T. D. Noe, Table of n, a(n) for n=1..10000` `Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.` `S. R. Finch, Idempotents and Nilpotents Modulo n (arXiv:math.NT/0605019)`
	FORMULA	`a(n) is equal to A010554 unless n is a member of A033949, in which case a(n)=0.`
	MATHEMATICA	`Prepend[ Table[ If[ IntegerQ[ PrimitiveRoot[n]] , EulerPhi[ EulerPhi[n]], 0], {n, 2, 91}], 1] (* From Jean-François Alcover, Sep 13 2011 *)`
	CROSSREFS	`Cf. A001918, A010554, A033949, A046145, A046146.` `Sequence in context: A112329 A117448 A093321 * A144736 A137423 A127471` `Adjacent sequences: A046141 A046142 A046143 * A046145 A046146 A046147`
	KEYWORD	`nonn`
	AUTHOR	`Eric Weisstein (eric(AT)weisstein.com)`

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Last modified February 15 08:20 EST 2012. Contains 205729 sequences.