"DHK" (bracelet, identity, unlabeled) transform of 2,2,2,2,...

Terms

a(0) =1a(1) =2a(2) =3a(3) =6a(4) =9a(5) =18a(6) =45a(7) =118a(8) =336a(9) =954a(10) =2695a(11) =7590a(12) =21321a(13) =59890a(14) =168273a(15) =473966a(16) =1337476a(17) =3785154a(18) =10738373a(19) =30546502a(20) =87099571a(21) =248937978a(22) =712995733a(23) =2046236598a(24) =5883318437a(25) =16944709370a(26) =48880145967a(27) =141211579446