A128404 Numbers k such that k^2 divides 24^k-1.

1, 23, 1081, 2870377, 7009273, 15954479, 134907719, 329435831, 537539141, 15001987199, 874750261127, 1991103024721, 4272172921319, 4862143429729, 7933540182019, 12816504745411, 41113262272969, 67084347257659

Offset: 1

Author

Alexander Adamchuk, Mar 01 2007

Keywords

• nonn
• less

Comments

23 divides all terms except the first.

Crossrefs

Cf. A127103, A127104, A127105, A127106, A127107, A127102, A127101, A127100, A127092, A128405, A128393, A128394, A128395, A128396, A128397, A128398, A128399, A128400, A128401, A128402, A128403.

Programs

Mathematica

a={}; Do[r=(24^n-1)/n^2; If[r==IntegerPart[r], AppendTo[a, n]], {n, 1, 10^3}]; a (* Vladimir Joseph Stephan Orlovsky, Aug 07 2008 *)

Extensions

a(5)-a(6) from Farideh Firoozbakht, Mar 05 2007

a(7)-a(10) from Ryan Propper, Feb 23 2008

Terms a(11) onward from Max Alekseyev, May 06 2010