OFFSET
1,3
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..13
FORMULA
a(n) = 2*a(n-1) - a(n-2) + (a(n-1)^2 + a(n-2)^2), with a(1) = a(2) = 1.
MATHEMATICA
a[n_]:= a[n]= If[n<3, 1, 2*a[n-1] -a[n-2] +(a[n-1]^2 + a[n-2]^2)];
Table[a[n], {n, 0, 10}]
PROG
(Magma)
function a(n) // a = A122591
if n lt 3 then return 1;
else return 2*a(n-1) -a(n-2) +(a(n-1)^2 +a(n-2)^2);
end if; return a; end function;
[a(n): n in [1..12]]; // G. C. Greubel, Nov 29 2021
(Sage)
#a = A122591
def a(n): return 1 if (n<3) else 2*a(n-1) -a(n-2) +(a(n-1)^2 +a(n-2)^2)
[a(n) for n in (1..12)] # G. C. Greubel, Nov 29 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Roger L. Bagula, Sep 19 2006
EXTENSIONS
Edited by N. J. A. Sloane, Sep 21 2006
STATUS
approved