id:A135347 - OEIS Search Results

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An inverse of the unitary totient function A047994.

+0
1

1, 3, 4, 5, -1, 7, 8, 9, -1, 11, -1, 13, -1, 24, 16, 17, -1, 19, -1, 33, -1, 23, -1, 25, -1, 27, -1, 29, -1, 31, 32, 45, -1, -1, -1, 37, -1, -1, -1, 41, -1, 43, -1, 69, -1, 47, -1, 49, -1, -1, -1, 53, -1, 76, -1, 72, -1, 59, -1, 61, -1, 96, 64, 85, -1, 67, -1, -1, -1, 71, -1, 73, -1, -1, -1, -1, -1, 79, -1, 81, -1, 83, -1, 104, -1, -1, -1 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`a(n) is the smallest m such that A047994(m)=n, or -1 if this m does not exist. Proof of non-existence may be done by transversing all A045778(n) factorizations of n, increasing each factor in these factorizations by 1, and showing that none of these modified products is a product of powers of distinct primes.`
	CROSSREFS	`Cf. A047994, A045778.` `Adjacent sequences: A135344 A135345 A135346 this_sequence A135348 A135349 A135350` `Sequence in context: A010263 A011303 A051993 this_sequence A009389 A091828 A121845`
	KEYWORD	`sign`
	AUTHOR	`R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Dec 07 2007`

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Last modified October 6 16:13 EDT 2008. Contains 144667 sequences.

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