a(0)=0, a(1)=1, a(n) = least k>a(n-1) such that k+a(n-2) is a Jacobsthal number.

Terms

a(0) =0a(1) =1a(2) =3a(3) =4a(4) =8a(5) =17a(6) =35a(7) =68a(8) =136a(9) =273a(10) =547a(11) =1092a(12) =2184a(13) =4369a(14) =8739a(15) =17476a(16) =34952a(17) =69905a(18) =139811a(19) =279620a(20) =559240a(21) =1118481a(22) =2236963a(23) =4473924a(24) =8947848a(25) =17895697a(26) =35791395a(27) =71582788a(28) =143165576a(29) =286331153