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

Terms

a(0) =1a(1) =4a(2) =13a(3) =37a(4) =97a(5) =241a(6) =577a(7) =1345a(8) =3073a(9) =6913a(10) =15361a(11) =33793a(12) =73729a(13) =159745a(14) =344065a(15) =737281a(16) =1572865a(17) =3342337a(18) =7077889a(19) =14942209a(20) =31457281a(21) =66060289a(22) =138412033a(23) =289406977a(24) =603979777a(25) =1258291201a(26) =2617245697a(27) =5435817985a(28) =11274289153a(29) =23353884673