a(n) = 3*a(n-1) - 3*a(n-3) + 2*a(n-4), with a(0)=4, a(1)=11.

Terms

a(0) =4a(1) =11a(2) =30a(3) =81a(4) =218a(5) =586a(6) =1575a(7) =4233a(8) =11377a(9) =30578a(10) =82185a(11) =220890a(12) =593690a(13) =1595671a(14) =4288713a(15) =11526849a(16) =30980914a(17) =83267945a(18) =223800714a(19) =601513098a(20) =1616697287a(21) =4345225609a(22) =11678738961a(23) =31389151218a(24) =84365171401