A013898 a(n) = 21^(5*n + 1).

21, 85766121, 350277500542221, 1430568690241985328321, 5842587018385982521381124421, 23861715484377209601555171628930521, 97453656071460446110921078004886769746621, 398010574215107679422058885600836061208944572721, 1625515384162495488635310116741260158419511738394408821

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

Comments

a(n) mod 10 == 1 (the least significant decimal digit of each term is 1).

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..50
• Tanya Khovanova, Recursive Sequences
• Index entries for linear recurrences with constant coefficients, signature (4084101).

Crossrefs

Cf. A009965.

Programs

Magma

[21^(5*n+1): n in [0..10]]; // Vincenzo Librandi, May 27 2011

Mathematica

NestList[4084101#&,21,10] (* Harvey P. Dale, Apr 17 2013 *)

Formula

a(n) = 4084101*a(n-1), a(0)=21. - Vincenzo Librandi, May 27 2011