a(n) = 3*a(n-1) - 2*a(n-2) with a(0)=28 and a(1)=70.

Terms

a(0) =28a(1) =70a(2) =154a(3) =322a(4) =658a(5) =1330a(6) =2674a(7) =5362a(8) =10738a(9) =21490a(10) =42994a(11) =86002a(12) =172018a(13) =344050a(14) =688114a(15) =1376242a(16) =2752498a(17) =5505010a(18) =11010034a(19) =22020082a(20) =44040178a(21) =88080370a(22) =176160754a(23) =352321522a(24) =704643058a(25) =1409286130a(26) =2818572274a(27) =5637144562a(28) =11274289138a(29) =22548578290