A121958 a(n) = a(n-2) + (n^2 - 3*n + 1)*a(n-1) with a(1)=0, a(2)=1, a(3)=1.

0, 1, 1, 6, 67, 1279, 37158, 1524757, 83898793, 5958339060, 530376075133, 57816950528557, 7574550895316100, 1174113205724524057, 212522064787034170417, 44418285653695866141210

Offset

1,4

Links

Robert Israel, Table of n, a(n) for n = 1..254

Formula

a(n) = a(n-2) + (n^2 - 3*n + 1)*a(n-1) with a(1)=0, a(2)=1, a(3)=1. - Robert Israel, Dec 18 2018

Maple

f:= gfun:-rectoproc({a(n) = a(n-2)+(n^2-3*n+1)*a(n-1), a(1)=0, a(2)=1}, a(n), remember):
map(f, [$1..30]); # Robert Israel, Dec 18 2018

Mathematica

M[n_] := {{0, 1}, {1, n^2 - n - 1} }
v[1] = {0, 1}
v[n_] := v[n] = M[n].v[n - 1]
Table[v[n][[1]], {n, 1, 30}]

Crossrefs

Sequence in context: A354320 A230342 A239301 * A177555 A054746 A116005

Adjacent sequences: A121955 A121956 A121957 * A121959 A121960 A121961

Keyword

nonn,easy

Author

Roger L. Bagula, Sep 02 2006

Extensions

Edited by Robert Israel, Dec 18 2018

New name (using Robert Israel's formula) from Joerg Arndt, Jan 06 2022

Status

approved