A107018 Belgian-7 numbers.

7, 10, 11, 21, 27, 29, 31, 32, 37, 41, 56, 70, 71, 77, 85, 94, 100, 101, 103, 106, 110, 111, 112, 113, 117, 118, 119, 122, 127, 128, 131, 133, 143, 152, 173, 176, 201, 205

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

a107018 n = a107018_list !! (n-1)
a107018_list = filter belge7 [7..] where
   belge7 x = x == (head $ dropWhile (< x) $
                     scanl (+) 7 $ 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@ 206, belgianQ[#, 7] &] (* Robert G. Wilson v, May 06 2011 *)

Extensions

Offset changed by Reinhard Zumkeller, May 08 2015