a(1) = 1; thereafter a(n) = Sum_{k = 1..n} a(k/gcd(n,k)).

Terms

a(0) =1a(1) =2a(2) =4a(3) =7a(4) =15a(5) =21a(6) =51a(7) =78a(8) =158a(9) =230a(10) =568a(11) =661a(12) =1797a(13) =2595a(14) =5117a(15) =7789a(16) =19095a(17) =21702a(18) =59892a(19) =81801a(20) =171329a(21) =258028a(22) =630942a(23) =713093a(24) =1887828a(25) =2776798a(26) =5727675a(27) =8335692a(28) =20702970a(29) =21420664