First partial sums of A005409; second partial sums of A001333.

Terms

a(0) =1a(1) =5a(2) =16a(3) =44a(4) =113a(5) =281a(6) =688a(7) =1672a(8) =4049a(9) =9789a(10) =23648a(11) =57108a(12) =137889a(13) =332913a(14) =803744a(15) =1940432a(16) =4684641a(17) =11309749a(18) =27304176a(19) =65918140a(20) =159140497a(21) =384199177a(22) =927538896a(23) =2239277016a(24) =5406092977a(25) =13051463021a(26) =31509019072a(27) =76069501220a(28) =183648021569a(29) =443365544417