OFFSET
1,3
REFERENCES
J. H. Conway, personal communication, Aug 27, 2001.
MATHEMATICA
r[n_, x_] := Reduce[n == x^2 + y^2 + z^2 + t^2, {y, z, t}, Integers]; solQ[n_, x_] := r[n, x] =!= False; ok[0] = True; ok[n_] := And @@ (solQ[n, #] & ) /@ Range[1, Sqrt[n - 1]]; A063950 = Select[ Select[ Range[0, 4000], Mod[#, 4] != 2 &], If[ok[#], Print[#]; True, False] &](* Jean-François Alcover, May 15 2012 *)
CROSSREFS
KEYWORD
nonn,easy,nice,fini,full
AUTHOR
N. J. A. Sloane, Sep 04 2001
EXTENSIONS
385 added by T. D. Noe, Apr 05 2007
STATUS
approved