Convolution of A000203 and A000009.

Terms

a(0) =0a(1) =1a(2) =4a(3) =8a(4) =16a(5) =25a(6) =42a(7) =61a(8) =90a(9) =130a(10) =178a(11) =242a(12) =332a(13) =436a(14) =566a(15) =747a(16) =952a(17) =1210a(18) =1540a(19) =1926a(20) =2400a(21) =2994a(22) =3674a(23) =4506a(24) =5526a(25) =6708a(26) =8108a(27) =9808a(28) =11768a(29) =14080