a(n) = ((5 + sqrt(18))*(2 + sqrt(8))^n + (5 - sqrt(18))*(2 - sqrt(8))^n)/2.

A164593

a(n) = ((5 + sqrt(18))*(2 + sqrt(8))^n + (5 - sqrt(18))*(2 - sqrt(8))^n)/2.

Terms

    a(0) =5a(1) =22a(2) =108a(3) =520a(4) =2512a(5) =12128a(6) =58560a(7) =282752a(8) =1365248a(9) =6592000a(10) =31828992a(11) =153683968a(12) =742051840a(13) =3582943232a(14) =17299980288a(15) =83531694080a(16) =403326697472

External references