a(n) = A087803(n) - n + 1.

Terms

a(0) =1a(1) =1a(2) =2a(3) =5a(4) =13a(5) =32a(6) =79a(7) =193a(8) =478a(9) =1196a(10) =3037a(11) =7802a(12) =20287a(13) =53259a(14) =141069a(15) =376449a(16) =1011295a(17) =2732453a(18) =7421128a(19) =20247355a(20) =55469186a(21) =152524366a(22) =420807220a(23) =1164532203a(24) =3231706847a(25) =8991343356a(26) =25075077684a(27) =70082143952a(28) =196268698259a(29) =550695545855