A089683 a(n) = 3^(4*n).

81, 6561, 531441, 43046721, 3486784401, 282429536481, 22876792454961, 1853020188851841, 150094635296999121, 12157665459056928801, 984770902183611232881, 79766443076872509863361, 6461081889226673298932241, 523347633027360537213511521, 42391158275216203514294433201

Offset

1,1

Links

Table of n, a(n) for n=1..15.

Tanya Khovanova, Recursive Sequences.

Index entries for linear recurrences with constant coefficients, signature (81).

Formula

a(n) = 81^n.

G.f.: 81*x/(1-81*x). - Philippe Deléham, Nov 25 2008

From Elmo R. Oliveira, Jul 09 2025: (Start)

E.g.f.: exp(81*x) - 1.

a(n) = 81*a(n-1) for n > 1.

a(n) = A001019(n)^2 = A000244(A008586(n)). (End)

Mathematica

3^(4*Range[20]) (* Harvey P. Dale, Apr 09 2012 *)
(* Alternative: *)
NestList[81#&, 81, 20] (* Harvey P. Dale, Apr 09 2012 *)

Prog

(PARI) my(x='x+O('x^16)); Vec(-81*x/(81*x-1)) \\ Elmo R. Oliveira, Jul 09 2025

Crossrefs

Cf. A000244, A001019, A008586, A009971.

Sequence in context: A223572 A188872 A217997 * A183506 A099372 A036515

Adjacent sequences: A089680 A089681 A089682 * A089684 A089685 A089686

Keyword

nonn,easy

Author

Douglas Winston (douglas.winston(AT)srupc.com), Jan 05 2004

Extensions

More terms from Harvey P. Dale, Apr 09 2012

Status

approved