First partial sums of A048739; second partial sums of A000129.

Terms

a(0) =1a(1) =4a(2) =12a(3) =32a(4) =81a(5) =200a(6) =488a(7) =1184a(8) =2865a(9) =6924a(10) =16724a(11) =40384a(12) =97505a(13) =235408a(14) =568336a(15) =1372096a(16) =3312545a(17) =7997204a(18) =19306972a(19) =46611168a(20) =112529329a(21) =271669848a(22) =655869048a(23) =1583407968a(24) =3822685009a(25) =9228778012a(26) =22280241060a(27) =53789260160a(28) =129858761409a(29) =313506783008