a(n) = 27^n * Sum_{k=0..n} binomial(-1/3, k)^2.
A367333
a(n) = 27^n * Sum_{k=0..n} binomial(-1/3, k)^2.
Terms
- a(0) =1a(1) =30a(2) =846a(3) =23430a(4) =643635a(5) =17601732a(6) =480016620a(7) =13065872292a(8) =355170348720
External references
- oeis: A367333