Zero together with the partial sums of A056640.

Terms

a(0) =0a(1) =1a(2) =6a(3) =24a(4) =66a(5) =149a(6) =292a(7) =520a(8) =860a(9) =1345a(10) =2010a(11) =2896a(12) =4046a(13) =5509a(14) =7336a(15) =9584a(16) =12312a(17) =15585a(18) =19470a(19) =24040a(20) =29370a(21) =35541a(22) =42636a(23) =50744a(24) =59956a(25) =70369a(26) =82082a(27) =95200a(28) =109830a(29) =126085