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A351987
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Numbers with factorial base expansion digits in nonincreasing order.
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2
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0, 1, 2, 3, 4, 5, 6, 8, 9, 12, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 30, 32, 33, 48, 54, 56, 57, 60, 62, 63, 64, 65, 72, 78, 80, 81, 84, 86, 87, 88, 89, 90, 92, 93, 94, 95, 96, 102, 104, 105, 108, 110, 111, 112, 113, 114, 116, 117, 118, 119, 120, 144, 150
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OFFSET
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1,3
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COMMENTS
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This sequence is to factorial base what A009996 is to decimal base.
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LINKS
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EXAMPLE
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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.
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MATHEMATICA
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max = 6; q[n_] := AllTrue[Differences @ IntegerDigits[n, MixedRadix[Range[max, 2, -1]]], # <= 0 &]; Select[Range[0, max!], q] (* Amiram Eldar, Feb 28 2022 *)
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PROG
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(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)) }
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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