Inverse Moebius transform applied twice to natural numbers.

Terms

a(0) =1a(1) =4a(2) =5a(3) =11a(4) =7a(5) =20a(6) =9a(7) =26a(8) =18a(9) =28a(10) =13a(11) =55a(12) =15a(13) =36a(14) =35a(15) =57a(16) =19a(17) =72a(18) =21a(19) =77a(20) =45a(21) =52a(22) =25a(23) =130a(24) =38a(25) =60a(26) =58a(27) =99a(28) =31a(29) =140