Position of n-th 5 in A031057.

Terms

a(0) =3a(1) =10a(2) =18a(3) =26a(4) =34a(5) =37a(6) =39a(7) =41a(8) =42a(9) =43a(10) =50a(11) =58a(12) =69a(13) =81a(14) =93a(15) =105a(16) =117a(17) =122a(18) =125a(19) =128a(20) =129a(21) =131a(22) =141a(23) =153a(24) =165a(25) =177a(26) =189a(27) =201a(28) =213a(29) =218