A225928 a(n) = 4*16^n + 8*4^n + 17.

29, 113, 1169, 16913, 264209, 4202513, 67141649, 1073872913, 17180393489, 274880004113, 4398054899729, 70368777732113, 1125900041060369, 18014399046352913, 288230378299195409, 4611686027017322513, 73786976329197944849, 1180591620854850256913

Offset: 0

Author

Eric M. Schmidt, May 21 2013

Keywords

• nonn
• easy

Comments

Number of conjugacy classes in Ree group 2F4(2*4^n).

Links

• Eric M. Schmidt, Table of n, a(n) for n = 0..500
• Frank Luebeck, Numbers of Conjugacy Classes in Finite Groups of Lie Type.
• Index entries for linear recurrences with constant coefficients, signature (21,-84,64).

Crossrefs

Cf. A188161, A224790, A225929 - A225938.

Programs

Mathematica

LinearRecurrence[{21,-84,64},{29,113,1169},20] (* Harvey P. Dale, May 06 2016 *)

PARI

a(n)=4*16^n+8*4^n+17 \\ Charles R Greathouse IV, May 22 2013

Sage

[4*16^n + 8*4^n + 17 for n in [0..20]]

Formula

G.f.: 17/(1-x) + 8/(1-4x) + 4/(1-16x).

a(n) = 21*a(n-1) - 84*a(n-2) + 64*a(n-3) for n > 2. - Wesley Ivan Hurt, Oct 08 2017