a(n) = ( (7 + sqrt(7))^n - (7 - sqrt(7))^n )/(2*sqrt(7)).

A154248

a(n) = ( (7 + sqrt(7))^n - (7 - sqrt(7))^n )/(2*sqrt(7)).

Terms

    a(0) =1a(1) =14a(2) =154a(3) =1568a(4) =15484a(5) =150920a(6) =1462552a(7) =14137088a(8) =136492048a(9) =1317130976a(10) =12707167648a(11) =122580846080

External references