a(n) = (1/n)*Sum_{i=0..n-1} C(n,i)*C(n,i+1)*6^i*7^(n-i), a(0)=1.
A133307
a(n) = (1/n)*Sum_{i=0..n-1} C(n,i)*C(n,i+1)*6^i*7^(n-i), a(0)=1.
Terms
- a(0) =1a(1) =7a(2) =91a(3) =1477a(4) =26845a(5) =522739a(6) =10663471a(7) =224939113a(8) =4866571801a(9) =107393779423
External references
- oeis: A133307