Position of n-th 4 in A031035.

Terms

a(0) =4a(1) =17a(2) =33a(3) =49a(4) =56a(5) =58a(6) =60a(7) =62a(8) =64a(9) =65a(10) =66a(11) =68a(12) =70a(13) =81a(14) =97a(15) =113a(16) =134a(17) =158a(18) =182a(19) =206a(20) =217a(21) =220a(22) =223a(23) =226a(24) =229a(25) =230a(26) =232a(27) =235a(28) =238a(29) =254