a(n) = (3*n+1)*2^n.

Terms

a(0) =1a(1) =8a(2) =28a(3) =80a(4) =208a(5) =512a(6) =1216a(7) =2816a(8) =6400a(9) =14336a(10) =31744a(11) =69632a(12) =151552a(13) =327680a(14) =704512a(15) =1507328a(16) =3211264a(17) =6815744a(18) =14417920a(19) =30408704a(20) =63963136a(21) =134217728a(22) =281018368a(23) =587202560a(24) =1224736768a(25) =2550136832a(26) =5301600256a(27) =11005853696a(28) =22817013760