Convolution of A000201 with itself.

Terms

a(0) =1a(1) =6a(2) =17a(3) =36a(4) =68a(5) =114a(6) =176a(7) =258a(8) =360a(9) =488a(10) =643a(11) =826a(12) =1045a(13) =1298a(14) =1588a(15) =1920a(16) =2292a(17) =2712a(18) =3180a(19) =3696a(20) =4269a(21) =4894a(22) =5579a(23) =6326a(24) =7133a(25) =8012a(26) =8958a(27) =9974a(28) =11068a(29) =12234