A108206 a(n)= 3*(n-1)*a(n-1) +(n-1)*a(n-2), with a(0)=1, a(1)=1.

0, 1, 3, 20, 189, 2348, 36165, 665058, 14219373, 346585416, 9485780589, 288039271830, 9609639556869, 349403495309244, 13751661631299813, 582461437448921562, 26417039609670967485, 1277337284263389184272

Offset

0,3

Comments

This is also the (2,2) element of the product matrix after multiplying the unit matrix from the

left by the matrices (0,1;j-1,3j-3) in the order j=2 to n.

Links

Table of n, a(n) for n=0..17.

Mathematica

M[n_] := {{0, 1}, {(n - 1), 3*(n - 1)}} v[1] = {0, 1} v[n_] := v[n] = M[n].v[n - 1] a = Table[Abs[v[n][[1]]], {n, 1, 25}]

Crossrefs

Cf. A000166.

Sequence in context: A208975 A286794 A176043 * A349959 A120485 A087152

Adjacent sequences: A108203 A108204 A108205 * A108207 A108208 A108209

Keyword

nonn,easy

Author

Roger L. Bagula, Jun 15 2005

Extensions

Definition replaced by recurrence by the Associate Editors of the OEIS, Sep 28 2009

Status

approved