Position of n-th 4 in A031219.

Terms

a(0) =4a(1) =14a(2) =24a(3) =34a(4) =35a(5) =37a(6) =39a(7) =41a(8) =43a(9) =44a(10) =59a(11) =74a(12) =89a(13) =104a(14) =106a(15) =109a(16) =112a(17) =115a(18) =118a(19) =119a(20) =134a(21) =149a(22) =164a(23) =179a(24) =181a(25) =184a(26) =187a(27) =190a(28) =193a(29) =194