Bi-unitary harmonic numbers.

Terms

a(0) =1a(1) =6a(2) =45a(3) =60a(4) =90a(5) =270a(6) =420a(7) =630a(8) =672a(9) =2970a(10) =5460a(11) =8190a(12) =9072a(13) =9100a(14) =10080a(15) =15925a(16) =22680a(17) =22848a(18) =27300a(19) =30240a(20) =40950a(21) =45360a(22) =54600a(23) =81900a(24) =95550a(25) =99792a(26) =136500a(27) =163800a(28) =172900a(29) =204750