cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A190218 Numbers all of whose divisors are numbers whose decimal digits are in strictly increasing order.

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%I A190218 #18 Feb 11 2019 01:25:06
%S A190218 1,2,3,4,5,6,7,8,9,12,13,14,15,16,17,18,19,23,24,25,26,27,28,29,34,35,
%T A190218 36,37,38,39,45,46,47,48,49,56,57,58,59,67,68,69,78,79,89,125,127,134,
%U A190218 135,136,137,138,139,145,149,157,158,167,169,178,179,235
%N A190218 Numbers all of whose divisors are numbers whose decimal digits are in strictly increasing order.
%C A190218 Sequence is finite. Last term a(163) = 23456789.
%C A190218 Subset of A009993. Superset of A052015.
%H A190218 Nathaniel Johnston and Jaroslav Krizek, <a href="/A190218/b190218.txt">Table of n, a(n) for n = 1..163</a> (complete list)
%e A190218 Number 135 is in sequence because all divisors of 135 (1, 3, 5, 9, 15, 27, 45, 135) are numbers whose decimal digits are in strictly increasing order.
%p A190218 with(numtheory): A190218 := 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(A190218(n), n=1..62); # _Nathaniel Johnston_, May 06 2011
%t A190218 Select[Range[250], And@@Positive[Flatten[Differences/@(IntegerDigits/@Divisors[#])]]&] (* _Harvey P. Dale_, Mar 24 2012 *)
%K A190218 nonn,fini,full,base
%O A190218 1,2
%A A190218 _Jaroslav Krizek_, May 06 2011