Principal diagonal of the convolution array A213553.

Terms

a(0) =1a(1) =43a(2) =334a(3) =1406a(4) =4271a(5) =10577a(6) =22764a(7) =44220a(8) =79437a(9) =134167a(10) =215578a(11) =332410a(12) =495131a(13) =716093a(14) =1009688a(15) =1392504a(16) =1883481a(17) =2504067a(18) =3278374a(19) =4233334a(20) =5398855a(21) =6807977a(22) =8497028a(23) =10505780a(24) =12877605a(25) =15659631a(26) =18902898a(27) =22662514