A013725 -id:A013725 - cp's OEIS frontend

A013724 a(n) = 19^(2*n + 1).

19, 6859, 2476099, 893871739, 322687697779, 116490258898219, 42052983462257059, 15181127029874798299, 5480386857784802185939, 1978419655660313589123979, 714209495693373205673756419

Offset: 0

N. J. A. Sloane

Vincenzo Librandi, Table of n, a(n) for n = 0..200
Tanya Khovanova, Recursive Sequences
Index entries for linear recurrences with constant coefficients, signature (361).

Bisection of A001029.

Cf. A013708-A013723, A013725-A013729.

[19^(2*n+1): n in [0..15]]; // Vincenzo Librandi, Jun 26 2011

seq(19^(2*n+1),n=0..10); # Nathaniel Johnston, Jun 25 2011

NestList[361#&,19,20] (* Harvey P. Dale, Jun 12 2017 *)

a(n)=19^(2*n+1) \\ Charles R Greathouse IV, Jul 11 2016

From Philippe Deléham, Nov 28 2008: (Start)
a(n) = 361*a(n-1); a(0)=19.
G.f.: 19/(1-361*x). (End)

A013726 a(n) = 21^(2*n + 1).

Original entry on oeis.org

21, 9261, 4084101, 1801088541, 794280046581, 350277500542221, 154472377739119461, 68122318582951682301, 30041942495081691894741, 13248496640331026125580781, 5842587018385982521381124421, 2576580875108218291929075869661, 1136272165922724266740722458520501

Offset: 0

N. J. A. Sloane

Vincenzo Librandi, Table of n, a(n) for n = 0..200
Tanya Khovanova, Recursive Sequences.
Index entries for linear recurrences with constant coefficients, signature (441).

Bisection of A009965 (21^n).

Cf. A005408, A013708-A013725, A013727-A013729.

[21^(2*n+1): n in [0..15]]; // Vincenzo Librandi, Jun 26 2011

seq(21^(2*n+1),n=0..10); # Nathaniel Johnston, Jun 25 2011

Table[21^(2 n + 1), {n, 0, 15}] (* Wesley Ivan Hurt, Feb 10 2014 *)

a(n)=21^(2*n+1) \\ Charles R Greathouse IV, Jul 11 2016

From Philippe Deléham, Nov 28 2008: (Start)
a(n) = 441*a(n-1); a(0)=21.
G.f.: 21/(1-441*x). (End)
a(n) = A009965(A005408(n)). - Wesley Ivan Hurt, Feb 10 2014
From Elmo R. Oliveira, Jul 10 2025: (Start)
E.g.f.: 21*exp(441*x).
a(n) = A013708(n)*A013712(n). (End)

cp's OEIS Frontend

A013724 a(n) = 19^(2*n + 1).

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