Jacobsthal numbers A001045 alternatingly incremented by 3 and 5.

Terms

a(0) =3a(1) =6a(2) =4a(3) =8a(4) =8a(5) =16a(6) =24a(7) =48a(8) =88a(9) =176a(10) =344a(11) =688a(12) =1368a(13) =2736a(14) =5464a(15) =10928a(16) =21848a(17) =43696a(18) =87384a(19) =174768a(20) =349528a(21) =699056a(22) =1398104a(23) =2796208a(24) =5592408a(25) =11184816a(26) =22369624a(27) =44739248a(28) =89478488a(29) =178956976