Partial sums of A006156.

Terms

a(0) =1a(1) =4a(2) =10a(3) =22a(4) =40a(5) =70a(6) =112a(7) =172a(8) =250a(9) =358a(10) =502a(11) =706a(12) =970a(13) =1312a(14) =1768a(15) =2386a(16) =3184a(17) =4228a(18) =5620a(19) =7450a(20) =9838a(21) =13018a(22) =17164a(23) =22582a(24) =29614a(25) =38812a(26) =50704a(27) =66190a(28) =86410a(29) =112834