A141825 Encodes permutations which "avoid" the subsequence "123" based on the mapping described in A051683.
0, 1, 2, 3, 4, 6, 7, 8, 9, 10, 12, 13, 16, 18, 24, 25, 26, 27, 28, 30, 31, 32, 33, 34, 36, 37, 40, 42, 48, 49, 50, 51, 52, 60, 61, 64, 66, 72, 73, 76, 90, 96
Offset: 1
Examples
The numbers 0 thru 4 map to 321,312,231,213 and 132 and are included because they avoid 123. The next number, 5, maps to 123 so is excluded from a(n).
Comments