a(n) = 4*a(n-1) - 2*a(n-2) + a(n-3) - 4*a(n-4) + 2*a(n-5) for n >= 7, where a(1) = 1, a(2) = 2, a(3) = 4, a(4) = 12, a(5) = 38, a(6) = 127.

A341240

a(n) = 4*a(n-1) - 2*a(n-2) + a(n-3) - 4*a(n-4) + 2*a(n-5) for n >= 7, where a(1) = 1, a(2) = 2, a(3) = 4, a(4) = 12, a(5) = 38, a(6) = 127.

Terms

    a(0) =1a(1) =2a(2) =4a(3) =12a(4) =38a(5) =127a(6) =432a(7) =1472a(8) =5023a(9) =17148a(10) =58544a(11) =199879a(12) =682428a(13) =2329952a(14) =7954951a(15) =27159900a(16) =92729696a(17) =316598983a(18) =1080936540a(19) =3690548192a(20) =12600319687a(21) =43020182364a(22) =146880090080a(23) =501479995591

External references