A045588 Numbers k that divide 9^k + 3^k.

1, 2, 3, 6, 9, 10, 18, 21, 27, 30, 50, 54, 63, 81, 90, 147, 150, 162, 171, 189, 243, 250, 270, 333, 438, 441, 450, 486, 513, 567, 729, 750, 810, 903, 999, 1029, 1197, 1250, 1314, 1323, 1350, 1458, 1539, 1701, 2187, 2190, 2250, 2331, 2430, 2709, 2997, 3087

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A074610.

Programs

Mathematica

Select[Range[3100],Divisible[9^#+3^#,#]&] (* Harvey P. Dale, Aug 13 2015 *)
Select[Range[300], Divisible[PowerMod[9, #, #] + PowerMod[3, #, #], #] &] (* Amiram Eldar, Oct 23 2021 *)