OFFSET
1,1
EXAMPLE
a(2) = 8 because the set of equations 1 +- x +- x^2 = 0 generates 8 distinct solutions.
MATHEMATICA
a[n_] := a[n] = Length[Union[ Flatten[x /. Table[Solve[1 + Sum[(-1)^IntegerDigits[k, 2, n + 1][[p + 1]]x^p, {p, n}] == 0], {k, 0, 2^n - 1}]]]]; Table[a[n], {n, 10}]
CROSSREFS
KEYWORD
more,nonn
AUTHOR
Josh Locker (jlocker(AT)mail.rochester.edu), Jul 26 2004
EXTENSIONS
More terms from Robert G. Wilson v and Labos Elemer, Jul 27 2004
a(17)-a(19) from Robert G. Wilson v, May 05 2013
a(20) from Robert G. Wilson v, May 05 2013
STATUS
approved