A106631 Belgian-4 numbers.

4, 10, 11, 13, 14, 20, 21, 22, 24, 25, 31, 32, 37, 40, 43, 44, 51, 54, 57, 64, 65, 76, 82, 84, 87, 89, 92, 98, 100, 101, 104, 110, 111, 112, 114, 116, 121, 122, 124, 125, 127, 128, 137, 140, 141, 142, 144, 145, 148, 149, 151, 154, 158, 172, 177, 191, 196

Offset: 1

Author

Eric Angelini, Jun 07 2005

Keywords

• base
• easy
• nonn

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

See A106039 for definition and link.

Belgian-k numbers, k=0..9: A106039, A106439, A106518, A106596, A106631, A106792, A107014, A107018, A107032, A107043.

Cf. A257770.

Programs

Haskell

a106631 n = a106631_list !! (n-1)
a106631_list = filter belge4 [4..] where
   belge4 x = x == (head $ dropWhile (< x) $
                    scanl (+) 4 $ cycle (map (read . return) $ show x))
-- Reinhard Zumkeller, May 08 2015

Mathematica

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 *)

Extensions

Offset changed by Reinhard Zumkeller, May 08 2015