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A190221
Numbers all of whose divisors are numbers whose decimal digits are in nondecreasing order.
2
1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19, 22, 23, 24, 25, 26, 27, 28, 29, 33, 34, 35, 36, 37, 38, 39, 44, 45, 46, 47, 48, 49, 55, 56, 57, 58, 59, 66, 67, 68, 69, 77, 78, 79, 88, 89, 99, 111, 112, 113, 114, 115, 116, 117, 118, 119, 125
OFFSET
1,2
COMMENTS
Subset of A009994. Superset of A028864, A190218 and A190217.
LINKS
EXAMPLE
Number 112 is in sequence because all divisors of 112 (1, 2, 4, 7, 8, 14, 16, 28, 56, 112) are numbers whose decimal digits are in nondecreasing order.
MAPLE
with(numtheory): A190221 := proc(n) option remember: local d, dd, i, j, k, m, poten: if(n=1)then return 1: fi: for k from procname(n-1)+1 do d:=divisors(k): poten:=1: for i from 1 to nops(d) do m:=10: dd:=convert(d[i], base, 10): for j from 1 to nops(dd) do if(m>=dd[j])then m:=dd[j]: else poten:=0: break: fi: od: if(poten=0)then break:fi: od: if(poten=1)then return k: fi: od: end: seq(A190221(n), n=1..64); # Nathaniel Johnston, May 06 2011
MATHEMATICA
ndoQ[n_]:=Min[Differences[IntegerDigits[n]]]>=0; Select[Range[ 200], AllTrue[ Divisors[#], ndoQ]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jun 02 2021 *)
CROSSREFS
Sequence in context: A009994 A239016 A102827 * A239215 A055571 A132781
KEYWORD
nonn,base
AUTHOR
Jaroslav Krizek, May 06 2011
STATUS
approved