a(n) = n + floor(Sum_{k<n} a(k)/2) with a(0)=0.

Terms

a(0) =0a(1) =1a(2) =2a(3) =4a(4) =7a(5) =12a(6) =19a(7) =29a(8) =45a(9) =68a(10) =103a(11) =156a(12) =235a(13) =353a(14) =531a(15) =797a(16) =1197a(17) =1796a(18) =2695a(19) =4044a(20) =6067a(21) =9101a(22) =13653a(23) =20480a(24) =30721a(25) =46083a(26) =69125a(27) =103689a(28) =155534a(29) =233302