A394342 a(n) = n*(3^n - 1) + 1.

1, 3, 17, 79, 321, 1211, 4369, 15303, 52481, 177139, 590481, 1948607, 6377281, 20726187, 66961553, 215233591, 688747521, 2195382755, 6973568785, 22082967855, 69735688001, 219667417243, 690383311377, 2165293112999, 6778308875521, 21182215236051, 66088511536529

Offset

0,2

Comments

A sequence that occurs in A394330.

Links

Paolo Xausa, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (8,-22,24,-9).

Formula

a(n) = A036290(n) + 1 - n.

a(n) = A050914(n) - n.

From Stefano Spezia, Mar 21 2026: (Start)

G.f.: (1 - 5*x + 15*x^2 - 15*x^3)/((1 - 3*x)^2*(1 - x)^2).

E.g.f.: exp(x)*(1 + (3*exp(2*x) - 1)*x). (End)

Mathematica

A394342[n_] := n*(3^n - 1) + 1; Array[A394342, 30, 0] (* or *)
LinearRecurrence[{8, -22, 24, -9}, {1, 3, 17, 79}, 30] (* Paolo Xausa, Mar 27 2026 *)

Crossrefs

Cf. A036290, A050914, A394330.

Sequence in context: A015525 A062224 A217958 * A093568 A164305 A202247

Adjacent sequences: A394339 A394340 A394341 * A394343 A394344 A394345

Keyword

nonn,easy

Author

A.H.M. Smeets, Mar 17 2026

Status

approved