Principal diagonal of the convolution array A213778.

Terms

a(0) =1a(1) =6a(2) =15a(3) =33a(4) =58a(5) =97a(6) =146a(7) =214a(8) =295a(9) =400a(10) =521a(11) =671a(12) =840a(13) =1043a(14) =1268a(15) =1532a(16) =1821a(17) =2154a(18) =2515a(19) =2925a(20) =3366a(21) =3861a(22) =4390a(23) =4978a(24) =5603a(25) =6292a(26) =7021a(27) =7819a(28) =8660a(29) =9575