id:A072917 - OEIS Search Results

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a(n) = p(n) - phi(n), where p(n) is the least prime greater than phi(n).

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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 3, 1, 1, 1, 3, 1, 1, 1, 3, 3, 1, 1, 1, 1, 3, 1, 1, 3, 1, 5, 1, 1, 1, 5, 1, 1, 1, 1, 3, 5, 1, 1, 1, 1, 3, 5, 5, 1, 1, 1, 5, 1, 1, 1, 1, 1, 1, 1, 5, 5, 3, 1, 5, 3, 5, 1, 5, 1, 1, 1, 1, 1, 5, 1, 5, 5, 1, 1, 5, 3, 1, 3, 1, 1, 5, 1, 3, 1, 1, 1, 5, 1, 1, 1, 1 (list; graph; listen)

	OFFSET	`1,15`
	EXAMPLE	`phi(15) = 8 and the least prime > 8 is 11; hence a(15) = 11 - 8 = 3.`
	MATHEMATICA	`a[n_] := Module[{r, p}, p = EulerPhi[n]; r = p + 1; While[ ! PrimeQ[r], r = r + 1]; r - p]; Table[a[i], {i, 1, 100}]`
	CROSSREFS	`Sequence in context: A114231 A079075 A086703 this_sequence A114266 A135910 A107333` `Adjacent sequences: A072914 A072915 A072916 this_sequence A072918 A072919 A072920`
	KEYWORD	`easy,nonn`
	AUTHOR	`Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Aug 11 2002`

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Last modified September 6 16:04 EDT 2008. Contains 143483 sequences.

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