a(1) = 1, a(n) = Sum_{k=1..n-1} (3^k - 1)/2 * a(k).
A015502
a(1) = 1, a(n) = Sum_{k=1..n-1} (3^k - 1)/2 * a(k).
Terms
- a(0) =1a(1) =1a(2) =5a(3) =70a(4) =2870a(5) =350140a(6) =127801100a(7) =139814403400
External references
- oeis: A015502
A015502
a(1) = 1, a(n) = Sum_{k=1..n-1} (3^k - 1)/2 * a(k).