a(n) = ((1 + 3*sqrt(2))*(2 + sqrt(2))^n + (1 - 3*sqrt(2))*(2 - sqrt(2))^n)/2.
A163613
a(n) = ((1 + 3*sqrt(2))*(2 + sqrt(2))^n + (1 - 3*sqrt(2))*(2 - sqrt(2))^n)/2.
Terms
- a(0) =1a(1) =8a(2) =30a(3) =104a(4) =356a(5) =1216a(6) =4152a(7) =14176a(8) =48400a(9) =165248a(10) =564192a(11) =1926272a(12) =6576704a(13) =22454272a(14) =76663680a(15) =261746176a(16) =893657344a(17) =3051137024a(18) =10417233408a(19) =35566659584a(20) =121432171520a(21) =414595366912
External references
- oeis: A163613