OFFSET
1,3
COMMENTS
This sequence is to factorial base what A009996 is to decimal base.
LINKS
Rémy Sigrist, Table of n, a(n) for n = 1..6910 (terms <= 9!)
EXAMPLE
The factorial base expansion of 102 is "4100", so 102 belongs to this sequence.
The factorial base expansion of 103 is "4101", so 103 does not belong to this sequence.
MATHEMATICA
max = 6; q[n_] := AllTrue[Differences @ IntegerDigits[n, MixedRadix[Range[max, 2, -1]]], # <= 0 &]; Select[Range[0, max!], q] (* Amiram Eldar, Feb 28 2022 *)
PROG
(PARI) is(n) = { my (p=0); for (r=2, oo, if (n==0, return (1)); my (d=n%r); if (d<p, return (0), p=d; n\=r)) }
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Rémy Sigrist, Feb 27 2022
STATUS
approved