Horadam sequence (0,1,6,4).

Terms

a(0) =0a(1) =1a(2) =4a(3) =22a(4) =112a(5) =580a(6) =2992a(7) =15448a(8) =79744a(9) =411664a(10) =2125120a(11) =10970464a(12) =56632576a(13) =292353088a(14) =1509207808a(15) =7790949760a(16) =40219045888a(17) =207621882112