Number of real singularities on a family of degree-3n algebraic surfaces.

Terms

a(0) =4a(1) =59a(2) =220a(3) =581a(4) =1162a(5) =2105a(6) =3370a(7) =5171a(8) =7384a(9) =10319a(10) =13744a(11) =18089a(12) =22990a(13) =29021a(14) =35662a(15) =43655a(16) =52300a(17) =62531a(18) =73444a(19) =86189a(20) =99634a(21) =115169a(22) =131410a(23) =150011a(24) =169312a(25) =191255a(26) =213880a(27) =239441a(28) =265654a(29) =295109