A031316 Position of n-th 3 in A031312.
2, 9, 19, 26, 28, 29, 30, 32, 34, 39, 49, 59, 69, 79, 89, 101, 116, 131, 142, 145, 146, 148, 151, 154, 161, 176, 191, 206, 221, 236, 251, 266, 281, 292, 295, 296, 298, 301, 304, 311, 326, 341, 356, 371, 386, 396, 399, 401, 402, 405
Offset: 1