Convolution of A001950 and A014306.

Terms

a(0) =0a(1) =2a(2) =7a(3) =12a(4) =19a(5) =30a(6) =42a(7) =57a(8) =75a(9) =93a(10) =114a(11) =137a(12) =162a(13) =191a(14) =222a(15) =255a(16) =292a(17) =330a(18) =372a(19) =414a(20) =457a(21) =504a(22) =553a(23) =605a(24) =660a(25) =716a(26) =777a(27) =839a(28) =903a(29) =972