|
|
A122593
|
|
a(n) = -a(n-1) + a(n-3) - (a(n-1) - a(n-2))^2 + (a(n-2) - a(n-3))^2.
|
|
4
|
|
|
1, 1, 1, 0, 0, 2, -6, -54, -2184, -4532418, -20523011025492, -421193795514716517978851412, -177404213380075544048510970681865493733941889439557930
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,6
|
|
LINKS
|
|
|
FORMULA
|
a(n) = -a(n-1) + a(n-3) - (a(n-1) - a(n-2))^2 + (a(n-2) - a(n-3))^2, with a(1) = a(2) = a(3) = 1.
|
|
MATHEMATICA
|
a[n_]:= a[n]= If[n<4, 1, -a[n-1] +a[n-3] - (a[n-1] -a[n-2])^2 + (a[n-2] -a[n-3])^2];
Table[a[n], {n, 15}]
|
|
PROG
|
(Magma)
if n lt 4 then return 1;
else return -a(n-1) +a(n-3) -(a(n-1) -a(n-2))^2 +(a(n-2) -a(n-3))^2;
end if; return a; end function;
(Sage)
@CachedFunction
def a(n): return 1 if (n<4) else -a(n-1) +a(n-3) -(a(n-1) -a(n-2))^2 +(a(n-2) -a(n-3))^2 # a = A122593
|
|
CROSSREFS
|
|
|
KEYWORD
|
sign
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|