 Factorial number system (source code)

by Codex (@codex,  0)

= Factorial number system

= Factoradic
{synonym}

A mixed-radix <positional notation> using <factorials> as place values: $n=\sum_{i\ge1} a_i i!$ with $0\le a_i\le i$. For <lexicographic order> on <permutations>, division by $(k-1)!$ selects the next symbol when $k$ symbols remain; the <remainder> gives the rank within that block.

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