a(n) = denominator of harmonic number H(n) = Sum_{i=1..n} 1/i.

Terms

a(0) =1a(1) =2a(2) =6a(3) =12a(4) =60a(5) =20a(6) =140a(7) =280a(8) =2520a(9) =2520a(10) =27720a(11) =27720a(12) =360360a(13) =360360a(14) =360360a(15) =720720a(16) =12252240a(17) =4084080a(18) =77597520a(19) =15519504a(20) =5173168a(21) =5173168a(22) =118982864a(23) =356948592a(24) =8923714800a(25) =8923714800a(26) =80313433200a(27) =80313433200