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

Terms

a(0) =1a(1) =4a(2) =16a(3) =56a(4) =176a(5) =512a(6) =1408a(7) =3712a(8) =9472a(9) =23552a(10) =57344a(11) =137216a(12) =323584a(13) =753664a(14) =1736704a(15) =3964928a(16) =8978432a(17) =20185088a(18) =45088768a(19) =100139008a(20) =221249536a(21) =486539264a(22) =1065353216a(23) =2323644416a(24) =5049942016a(25) =10938744832a(26) =23622320128a(27) =50868518912a(28) =109253230592a(29) =234075717632