Total number of elements in all subsets of {1,2,..,n} with relatively prime elements.

Terms

a(0) =1a(1) =3a(2) =10a(3) =27a(4) =74a(5) =176a(6) =431a(7) =987a(8) =2259a(9) =5025a(10) =11168a(11) =24351a(12) =53022a(13) =114204a(14) =245221a(15) =523173a(16) =1112996a(17) =2356796a(18) =4978235a(19) =10480426a(20) =22014499a(21) =46125601a(22) =96457248a(23) =201300980a(24) =419404740a(25) =872360898a(26) =1811883714a(27) =3757979313a(28) =7784511152