a(n) = (H(n) - 1)*lcm{1,...,n}, where H(n) is the n-th harmonic number.

Terms

a(0) =0a(1) =1a(2) =5a(3) =13a(4) =77a(5) =87a(6) =669a(7) =1443a(8) =4609a(9) =4861a(10) =55991a(11) =58301a(12) =785633a(13) =811373a(14) =835397a(15) =1715839a(16) =29889983a(17) =30570663a(18) =593094837a(19) =604734465a(20) =615819825a(21) =626401305a(22) =14640022575a(23) =14863115445a(24) =75386423001a(25) =76416082401a(26) =232222818803a(27) =235091155703