A160569 a(n)=9*(a(n-1)a(n-3)-a(n-2)^2)/a(n-4), a(1)=a(2)=a(3)=1, a(4)=-9.

1, 1, 1, -9, -90, -1539, 51759, 7026831, 1349328699, -119669884380, -462804380329131, -818173230956710191, -775566981773559330471, 23349606875054800260574779, 383206716517298992863985977570

Offset

0,4

Comments

a(n+1) is the Hankel transform of A160568.

Links

Harvey P. Dale, Table of n, a(n) for n = 0..79

Mathematica

nxt[{a_, b_, c_, d_}]:={b, c, d, (9(d*b-c^2))/a}; NestList[nxt, {1, 1, 1, -9}, 20][[All, 1]] (* Harvey P. Dale, Feb 21 2022 *)

Crossrefs

Cf. A050512, A160566.

Sequence in context: A294610 A294813 A218118 * A157545 A274953 A157558

Adjacent sequences: A160566 A160567 A160568 * A160570 A160571 A160572

Keyword

easy,sign

Author

Paul Barry, May 19 2009

Status

approved