A031002 Position of n-th 3 in A030998.
3, 14, 28, 35, 37, 39, 41, 42, 43, 45, 47, 56, 70, 84, 102, 123, 144, 155, 158, 161, 164, 165, 167, 170, 173, 186, 207, 228, 249, 270, 291, 302, 305, 308, 311, 312, 314, 317, 320, 333, 354, 375, 385, 388, 391, 394, 396, 397, 400
Offset: 1