a(n) = ((4 + 3*sqrt(2))*(1 + 2*sqrt(2))^n + (4 - 3*sqrt(2))*(1 - 2*sqrt(2))^n)/8.
A164589
a(n) = ((4 + 3*sqrt(2))*(1 + 2*sqrt(2))^n + (4 - 3*sqrt(2))*(1 - 2*sqrt(2))^n)/8.
Terms
- a(0) =1a(1) =4a(2) =15a(3) =58a(4) =221a(5) =848a(6) =3243a(7) =12422a(8) =47545a(9) =182044a(10) =696903a(11) =2668114a(12) =10214549a(13) =39105896a(14) =149713635a(15) =573168542a(16) =2194332529a(17) =8400844852a(18) =32162017407a(19) =123129948778a(20) =471394019405
External references
- oeis: A164589