Convolution square of A058187, the tetrahedral series with repeats.

Terms

a(0) =1a(1) =2a(2) =9a(3) =16a(4) =44a(5) =72a(6) =156a(7) =240a(8) =450a(9) =660a(10) =1122a(11) =1584a(12) =2508a(13) =3432a(14) =5148a(15) =6864a(16) =9867a(17) =12870a(18) =17875a(19) =22880a(20) =30888a(21) =38896a(22) =51272a(23) =63648a(24) =82212a(25) =100776a(26) =127908a(27) =155040a(28) =193800a(29) =232560