Sum of squares of first n positive integers congruent to 1 mod 3.

Terms

a(0) =1a(1) =17a(2) =66a(3) =166a(4) =335a(5) =591a(6) =952a(7) =1436a(8) =2061a(9) =2845a(10) =3806a(11) =4962a(12) =6331a(13) =7931a(14) =9780a(15) =11896a(16) =14297a(17) =17001a(18) =20026a(19) =23390a(20) =27111a(21) =31207a(22) =35696a(23) =40596a(24) =45925a(25) =51701a(26) =57942a(27) =64666a(28) =71891a(29) =79635