A013766 a(n) = 20^(3*n + 1).

20, 160000, 1280000000, 10240000000000, 81920000000000000, 655360000000000000000, 5242880000000000000000000, 41943040000000000000000000000, 335544320000000000000000000000000, 2684354560000000000000000000000000000, 21474836480000000000000000000000000000000

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..200
• Tanya Khovanova, Recursive Sequences.
• Index entries for linear recurrences with constant coefficients, signature (8000).

Crossrefs

Subsequence of A009964.

Cf. A013730, A013746, A016777.

Programs

Magma

[20^(3*n+1): n in [0..10]]; // Vincenzo Librandi, Jun 27 2011

Mathematica

20^(3Range[0,10]+1) (* Harvey P. Dale, Jun 23 2011 *)

Maxima

makelist(20^(3*n+1),n,0,20); /* Martin Ettl, Oct 21 2012 */

PARI

a(n)=20^(3*n+1) \\ Charles R Greathouse IV, Jul 10 2016

Formula

From Elmo R. Oliveira, Feb 27 2025: (Start)

G.f.: 20/(1 - 8000*x).

E.g.f.: 20*exp(8000*x).

a(n) = A013730(n)*A013746(n) = A009964(A016777(n)). (End)