a(n) = denominator of b(n), where b(1) = 1, b(n) = Sum_{k=1..n-1} b(n-k) * H(k); H(k) = Sum_{j=1..k} 1/j, the k-th harmonic number.

A128045

a(n) = denominator of b(n), where b(1) = 1, b(n) = Sum_{k=1..n-1} b(n-k) * H(k); H(k) = Sum_{j=1..k} 1/j, the k-th harmonic number.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =6a(4) =2a(5) =5a(6) =360a(7) =2520a(8) =1680a(9) =15120a(10) =2700a(11) =11880a(12) =9979200a(13) =8648640a(14) =18345600a(15) =2476656000a(16) =27243216000a(17) =714714000a(18) =427508928000

External references