Main diagonal of array A[k,n] = n-th sum of 3 consecutive k-gonal numbers, k>2.

Terms

a(0) =4a(1) =14a(2) =39a(3) =88a(4) =170a(5) =294a(6) =469a(7) =704a(8) =1008a(9) =1390a(10) =1859a(11) =2424a(12) =3094a(13) =3878a(14) =4785a(15) =5824a(16) =7004a(17) =8334a(18) =9823a(19) =11480a(20) =13314a(21) =15334a(22) =17549a(23) =19968a(24) =22600a(25) =25454a(26) =28539a(27) =31864a(28) =35438a(29) =39270