Convolution of nonzero hexagonal numbers (A000384) with themselves.

Terms

a(0) =1a(1) =12a(2) =66a(3) =236a(4) =651a(5) =1512a(6) =3108a(7) =5832a(8) =10197a(9) =16852a(10) =26598a(11) =40404a(12) =59423a(13) =85008a(14) =118728a(15) =162384a(16) =218025a(17) =287964a(18) =374794a(19) =481404a(20) =610995a(21) =767096a(22) =953580a(23) =1174680a(24) =1435005a(25) =1739556a(26) =2093742a(27) =2503396a(28) =2974791a(29) =3514656