Number of subsets of {1..n} whose elements have the same number of divisors.

Terms

a(0) =1a(1) =2a(2) =3a(3) =5a(4) =6a(5) =10a(6) =11a(7) =19a(8) =21a(9) =23a(10) =27a(11) =43a(12) =44a(13) =76a(14) =84a(15) =100a(16) =101a(17) =165a(18) =167a(19) =295a(20) =299a(21) =331a(22) =395a(23) =651a(24) =652a(25) =656a(26) =784a(27) =1040a(28) =1048a(29) =1560