a(n) = 2 + 4^(n - 1) - (2 - sqrt(2))^(n - 1) - (2 + sqrt(2))^(n - 1).
A377501
a(n) = 2 + 4^(n - 1) - (2 - sqrt(2))^(n - 1) - (2 + sqrt(2))^(n - 1).
Terms
- a(0) =1a(1) =2a(2) =6a(3) =26a(4) =122a(5) =562a(6) =2514a(7) =10978a(8) =47074a(9) =199106a(10) =833346a(11) =3459458a(12) =14268290a(13) =58542850a(14) =239189250a(15) =973889026a(16) =3954048514a(17) =16015899650a(18) =64745436162a(19) =261309683714
External references
- oeis: A377501