Convolution of nonzero octagonal numbers (A000567) with themselves.

Terms

a(0) =1a(1) =16a(2) =106a(3) =416a(4) =1211a(5) =2912a(6) =6132a(7) =11712a(8) =20757a(9) =34672a(10) =55198a(11) =84448a(12) =124943a(13) =179648a(14) =252008a(15) =345984a(16) =466089a(17) =617424a(18) =805714a(19) =1037344a(20) =1319395a(21) =1659680a(22) =2066780a(23) =2550080a(24) =3119805a(25) =3787056a(26) =4563846a(27) =5463136a(28) =6498871a(29) =7686016