A097884 First differences of A097605 (phi(n) divides n^2 - 1).

1, 1, 2, 2, 4, 2, 2, 2, 2, 4, 6, 2, 4, 2, 4, 2, 4, 6, 6, 2, 4, 2, 4, 2, 6, 4, 6, 2, 6, 4, 2, 4, 2, 4, 14, 4, 6, 2, 10, 2, 6, 6, 4, 6, 6, 2, 10, 2, 4, 2, 12, 12, 4, 2, 4, 6, 2, 10, 4, 2, 6, 6, 2, 6, 4, 2, 10, 14, 4, 2, 4, 14, 6, 10, 2, 4, 6, 8, 6, 4, 2, 4, 6, 8, 4, 8, 10, 2, 10, 2, 6, 4, 6, 8, 4, 2, 4, 12, 8

Offset

1,3

Links

G. C. Greubel, Table of n, a(n) for n = 1..1000

Mathematica

A097605:= Select[Range[500], Mod[#^2 - 1, EulerPhi[#]] == 0 &]
Table[A097605[[n]] - A097605[[n - 1]], {n, 2, 50}] (* G. C. Greubel, Dec 21 2017 *)

Crossrefs

Cf. A097605.

Sequence in context: A092188 A340675 A356497 * A094818 A114233 A279047

Adjacent sequences: A097881 A097882 A097883 * A097885 A097886 A097887

Keyword

nonn

Author

John W. Layman, Sep 02 2004

Status

approved