A015871 Numbers k such that phi(k + 5) | sigma(k) + 5.

1, 4, 9, 16, 18, 64, 81, 729, 4096, 59049, 125316, 262144, 16777216

Offset

1,2

Comments

a(14) > 10^12. - Donovan Johnson, Feb 28 2012

Links

Table of n, a(n) for n=1..13.

Mathematica

Select[Range[100000],
Divisible[DivisorSigma[1, #] + 5, EulerPhi[# + 5]] &] (* David Nacin, Feb 28 2012 *)

Crossrefs

Sequence in context: A332443 A313323 A313324 * A035234 A313325 A313326

Adjacent sequences: A015868 A015869 A015870 * A015872 A015873 A015874

Keyword

nonn

Author

Robert G. Wilson v

Extensions

Offset corrected and a(11)-a(13) from Donovan Johnson, Feb 28 2012

Status

approved