OFFSET
1,2
FORMULA
a(n)=a(n - 1)^2 - 2*a(n - 1) - a(n - 2)^2 + 2*a(n - 2).
log a(n) ~ 0.011287... * 2^n - Charles R Greathouse IV, Oct 06 2009
MATHEMATICA
Clear[a, n]; a[0] = 1; a[1] = 2; a[n_] := a[n] = a[n - 1]^2 - 2*a[n - 1] - a[n - 2]^2 + 2*a[n - 2]; Table[a[n], {n, 0, 15}]
nxt[{a_, b_}]:={b, b^2-2b-a^2+2a}; NestList[nxt, {1, 2}, 15][[All, 1]] (* Harvey P. Dale, Aug 15 2021 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Roger L. Bagula and Gary W. Adamson, Oct 23 2008
EXTENSIONS
Corrected by Harvey P. Dale, Aug 15 2021
STATUS
approved