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.
%I A287336 #12 Mar 03 2024 10:15:51
%S A287336 1,2,3,4,5,6,7,8,9,15,18,45,111,126,222,285,333,444,555,666,777,888,
%T A287336 999,1041,1185,1395,1443,1554,1665,1893,1998,2082,2331,2528,2757,2886,
%U A287336 3885,4662,4995,6055,6993,7245,10101,11111,11655,12321,12987,13206,13986
%N A287336 Numbers k, not ending in 0, such that inserting a 0 between each pair of adjacent digits results in a multiple of k.
%C A287336 Sequence is infinite since it contains all the numbers of the form (10^(2*t+1)-1)/9, i.e., repunits with an odd number of digits, like 111, 11111, and so on (A100706).
%H A287336 Giovanni Resta, <a href="/A287336/b287336.txt">Table of n, a(n) for n = 1..600</a>
%e A287336 41499585 is a term because 401040909050805 is a multiple of 41499585.
%t A287336 ins[n_, c_] := Block[{d = IntegerDigits[n]}, FromDigits@ Most@ Flatten@ Transpose[{d, c + 0 Range[Length@d]}]]; Select[Range[10^5], Mod[#, 10] > 0 && Mod[ins[#, 0], #] == 0 &]
%Y A287336 Cf. A285176.
%K A287336 nonn,base
%O A287336 1,2
%A A287336 _Giovanni Resta_, May 23 2017