Denominator of Sum_{k=1..n} 1/sigma(k).

Terms

a(0) =1a(1) =3a(2) =12a(3) =84a(4) =28a(5) =42a(6) =168a(7) =280a(8) =3640a(9) =32760a(10) =32760a(11) =32760a(12) =4680a(13) =1170a(14) =4680a(15) =145080a(16) =145080a(17) =145080a(18) =145080a(19) =1015560a(20) =4062240a(21) =4062240a(22) =4062240a(23) =4062240a(24) =4062240a(25) =4062240a(26) =4062240a(27) =4062240a(28) =4062240a(29) =4062240