Partial sums of A053519.

Terms

a(0) =1a(1) =4a(2) =19a(3) =48a(4) =645a(5) =5346a(6) =9989a(7) =423680a(8) =4936673a(9) =22863284a(10) =717864203a(11) =10398234146a(12) =14778845999