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 A127424 #8 Mar 29 2017 04:18:53
%S A127424 210,321,432,543,654,765,876,987,1098,11109,121110,131211,141312,
%T A127424 151413,161514,171615,181716,191817,201918,212019,222120,232221,
%U A127424 242322,252423,262524,272625,282726,292827,302928,313029,323130,333231,343332,353433,363534
%N A127424 Numbers whose decimal expansion is a concatenation of 3 consecutive decreasing numbers.
%e A127424 a(13)=141312 because 14 and 13 and 12 are three consecutive decreasing numbers
%t A127424 Table[FromDigits[Flatten[IntegerDigits[#]&/@Range[n,n-2,-1]]],{n,2,40}] (* _Harvey P. Dale_, Nov 28 2013 *)
%Y A127424 Cf. A127421-A127424.
%K A127424 nonn,base
%O A127424 1,1
%A A127424 _Artur Jasinski_, Jan 14 2007
%E A127424 Corrected and extended by _Harvey P. Dale_, Nov 28 2013