a(n) = (4*a(n-1)*a(n-3) + a(n-2)^2)/a(n-4), with a(1)=...=a(4)=1.
A121881
a(n) = (4*a(n-1)*a(n-3) + a(n-2)^2)/a(n-4), with a(1)=...=a(4)=1.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =5a(5) =21a(6) =109a(7) =2621a(8) =46409a(9) =1290665a(10) =143900249a(11) =10827502009
External references
- oeis: A121881