a(n) = A000984(n) + n.

Terms

a(0) =1a(1) =3a(2) =8a(3) =23a(4) =74a(5) =257a(6) =930a(7) =3439a(8) =12878a(9) =48629a(10) =184766a(11) =705443a(12) =2704168a(13) =10400613a(14) =40116614a(15) =155117535a(16) =601080406a(17) =2333606237a(18) =9075135318a(19) =35345263819a(20) =137846528840a(21) =538257874461