a(n) = Sum_{k=0..n} 9^(n-k) * binomial(n+k-1,k) * binomial(k/3,n-k).
A378555
a(n) = Sum_{k=0..n} 9^(n-k) * binomial(n+k-1,k) * binomial(k/3,n-k).
Terms
- a(0) =1a(1) =1a(2) =9a(3) =19a(4) =305a(5) =156a(6) =13233a(7) =-23988a(8) =688113a(9) =-2863070a(10) =41085704a(11) =-246536784a(12) =2696513885a(13) =-19410931916a(14) =187672944300
External references
- oeis: A378555