Main diagonal of square arrays A114881 and A249741.

Terms

a(0) =1a(1) =8a(2) =34a(3) =90a(4) =208a(5) =376a(6) =628a(7) =816a(8) =1218a(9) =1768a(10) =2200a(11) =2922a(12) =3648a(13) =4342a(14) =5028a(15) =5988a(16) =7728a(17) =8478a(18) =10116a(19) =11572a(20) =12628a(21) =14298a(22) =16018a(23) =17710a(24) =21630a(25) =23128a(26) =24616a(27) =26856a(28) =28666a(29) =30622