a(0)=2, a(1)=7, and a(n) = (3*n+1)*2^(n-1) if n > 1.

Terms

a(0) =2a(1) =7a(2) =14a(3) =40a(4) =104a(5) =256a(6) =608a(7) =1408a(8) =3200a(9) =7168a(10) =15872a(11) =34816a(12) =75776a(13) =163840a(14) =352256a(15) =753664a(16) =1605632a(17) =3407872a(18) =7208960a(19) =15204352a(20) =31981568a(21) =67108864a(22) =140509184a(23) =293601280a(24) =612368384a(25) =1275068416a(26) =2650800128a(27) =5502926848a(28) =11408506880a(29) =23622320128