Partial sums of A211681.

Terms

a(0) =2a(1) =5a(2) =10a(3) =17a(4) =40a(5) =77a(6) =130a(7) =203a(8) =440a(9) =813a(10) =1350a(11) =2087a(12) =4460a(13) =8197a(14) =13570a(15) =20943a(16) =44680a(17) =82053a(18) =135790a(19) =209527a(20) =446900a(21) =820637a(22) =1358010a(23) =2095383a(24) =4469120a(25) =8206493a(26) =13580230a(27) =20953967a(28) =44691340a(29) =82065077