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
KEYWORD
easy,sign
AUTHOR
Paul Barry, May 19 2009
STATUS
approved