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A015971 k is the first integer such that phi(k + n) | sigma(k). 0
1, 1, 3, 3, 5, 3, 6, 3, 6, 3, 11, 15, 6, 5, 14, 6, 14, 7, 24, 21, 6, 14, 6, 7, 15, 11, 24, 15, 10, 20, 6, 11, 22, 23, 45, 22, 6, 15, 14, 21, 30, 15, 14, 21, 10, 33, 12, 19, 27, 23, 62, 33, 22, 24, 22, 15, 14, 15, 14, 21, 26, 23, 42, 15, 14, 30, 20, 23, 46, 15, 14, 31, 26 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..72.

MATHEMATICA

Table[k = 1; While[! Divisible[DivisorSigma[1, k], EulerPhi[k + n]], k++]; k, {n, 0, 72}] (* Jayanta Basu, Jul 25 2013 *)

CROSSREFS

Sequence in context: A033558 A046217 A057662 * A163167 A243729 A200810

Adjacent sequences:  A015968 A015969 A015970 * A015972 A015973 A015974

KEYWORD

nonn

AUTHOR

Robert G. Wilson v

STATUS

approved

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Last modified September 23 20:42 EDT 2021. Contains 347617 sequences. (Running on oeis4.)