a(n) = Sum_{k=1..n} 2^(T(k)-1), where T(k)=k(k+1)/2 = A000217(k).
A246534
a(n) = Sum_{k=1..n} 2^(T(k)-1), where T(k)=k(k+1)/2 = A000217(k).
Terms
- a(0) =0a(1) =1a(2) =5a(3) =37a(4) =549a(5) =16933a(6) =1065509a(7) =135283237a(8) =34495021605
External references
- oeis: A246534