cp's OEIS Frontend

A190221 Numbers all of whose divisors are numbers whose decimal digits are in nondecreasing order.

%I A190221 #10 Jun 02 2021 13:54:35
%S A190221 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,
%T A190221 33,34,35,36,37,38,39,44,45,46,47,48,49,55,56,57,58,59,66,67,68,69,77,
%U A190221 78,79,88,89,99,111,112,113,114,115,116,117,118,119,125
%N A190221 Numbers all of whose divisors are numbers whose decimal digits are in nondecreasing order.
%C A190221 Subset of A009994. Superset of A028864, A190218 and A190217.
%H A190221 Nathaniel Johnston, <a href="/A190221/b190221.txt">Table of n, a(n) for n = 1..1000</a>
%e A190221 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.
%p A190221 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
%t A190221 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 *)
%K A190221 nonn,base
%O A190221 1,2
%A A190221 _Jaroslav Krizek_, May 06 2011