Convolution of A000203 with itself.

Terms

a(0) =1a(1) =6a(2) =17a(3) =38a(4) =70a(5) =116a(6) =185a(7) =258a(8) =384a(9) =490a(10) =686a(11) =826a(12) =1124a(13) =1292a(14) =1705a(15) =1896a(16) =2491a(17) =2670a(18) =3416a(19) =3680a(20) =4602a(21) =4796a(22) =6110a(23) =6178a(24) =7700a(25) =7980a(26) =9684a(27) =9730a(28) =12156a(29) =11920