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 A106631 #15 May 08 2015 16:51:00
%S A106631 4,10,11,13,14,20,21,22,24,25,31,32,37,40,43,44,51,54,57,64,65,76,82,
%T A106631 84,87,89,92,98,100,101,104,110,111,112,114,116,121,122,124,125,127,
%U A106631 128,137,140,141,142,144,145,148,149,151,154,158,172,177,191,196
%N A106631 Belgian-4 numbers.
%H A106631 Reinhard Zumkeller, <a href="/A106631/b106631.txt">Table of n, a(n) for n = 1..10000</a>
%t A106631 belgianQ[n_, k_] := If[n < k, False, Block[{id = Join[{0}, IntegerDigits@ n]}, MemberQ[ Accumulate@ id, Mod[n - k, Plus @@ id]] ]]; Select[ Range@ 199, belgianQ[#, 4] &] (* _Robert G. Wilson v_, May 06 2011 *)
%o A106631 (Haskell)
%o A106631 a106631 n = a106631_list !! (n-1)
%o A106631 a106631_list = filter belge4 [4..] where
%o A106631 belge4 x = x == (head $ dropWhile (< x) $
%o A106631 scanl (+) 4 $ cycle (map (read . return) $ show x))
%o A106631 -- _Reinhard Zumkeller_, May 08 2015
%Y A106631 See A106039 for definition and link.
%Y A106631 Belgian-k numbers, k=0..9: A106039, A106439, A106518, A106596, A106631, A106792, A107014, A107018, A107032, A107043.
%Y A106631 Cf. A257770.
%K A106631 base,easy,nonn
%O A106631 1,1
%A A106631 _Eric Angelini_, Jun 07 2005
%E A106631 Offset changed by _Reinhard Zumkeller_, May 08 2015