Position of n-th 5 in A030588.

Terms

a(0) =3a(1) =9a(2) =15a(3) =21a(4) =27a(5) =28a(6) =30a(7) =32a(8) =33a(9) =42a(10) =51a(11) =60a(12) =69a(13) =78a(14) =80a(15) =83a(16) =86a(17) =87a(18) =96a(19) =105a(20) =114a(21) =123a(22) =132a(23) =134a(24) =137a(25) =140a(26) =141a(27) =150a(28) =159a(29) =168