Number of ordered triples (w,x,y) with all terms in {-n,...-1,1,...,n} and w+x+y>=0.

Terms

a(0) =0a(1) =4a(2) =35a(3) =117a(4) =274a(5) =530a(6) =909a(7) =1435a(8) =2132a(9) =3024a(10) =4135a(11) =5489a(12) =7110a(13) =9022a(14) =11249a(15) =13815a(16) =16744a(17) =20060a(18) =23787a(19) =27949a(20) =32570a(21) =37674a(22) =43285a(23) =49427a(24) =56124a(25) =63400a(26) =71279a(27) =79785a(28) =88942a(29) =98774