a(1) = 1, a(n) = Sum_{k=1..n-1} ((7^k - 1)/6)*a(k).
A015508
a(1) = 1, a(n) = Sum_{k=1..n-1} ((7^k - 1)/6)*a(k).
Terms
- a(0) =1a(1) =1a(2) =9a(3) =522a(4) =209322a(5) =586520244
External references
- oeis: A015508
A015508
a(1) = 1, a(n) = Sum_{k=1..n-1} ((7^k - 1)/6)*a(k).