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 A140281 #7 May 17 2016 10:38:28
%S A140281 0,1,2,3,4,5,6,7,8,9,20,21,22,23,24,25,26,27,28,29,40,41,42,43,44,45,
%T A140281 46,47,48,49,60,61,62,63,64,65,66,67,68,69,80,81,82,83,84,85,86,87,88,
%U A140281 89,300,301,302,303,304,305,306,307,308,309,320,321,322,323,324,325,326
%N A140281 A Diophantine equation over digits of n. Numbers n such that x_1/r +x_2/r-1 + ... + x_r/1 = k; x_i digits of n; k integer.
%e A140281 n=321 : 3/3 + 2/2 + 1/1 = 3, 321 belongs to the sequence
%t A140281 Join[{0},Select[Range[400],IntegerQ[Total[IntegerDigits[#]/Reverse[ Range[ IntegerLength[ #]]]]]&]] (* _Harvey P. Dale_, May 17 2016 *)
%Y A140281 Cf. A005349, A137923, A138566, A139749, A139750, .
%K A140281 easy,nonn,base
%O A140281 0,3
%A A140281 _Ctibor O. Zizka_, May 23 2008