a(n) = floor(n*2*(3^n-2^n)/2^n).

Terms

a(0) =1a(1) =5a(2) =14a(3) =32a(4) =65a(5) =124a(6) =225a(7) =394a(8) =673a(9) =1133a(10) =1880a(11) =3089a(12) =5034a(13) =8146a(14) =13106a(15) =20986a(16) =33464a(17) =53168a(18) =84201a(19) =132970a(20) =209449a(21) =329156a(22) =516200a(23) =807989a(24) =1262508a(25) =1969539a(26) =3067962a(27) =4772414a(28) =7414316a(29) =11505003