A258217 Smallest multiple of 7 starting with n, that did not appear earlier.

14, 21, 35, 42, 56, 63, 7, 84, 91, 105, 112, 126, 133, 140, 154, 161, 175, 182, 196, 203, 210, 224, 231, 245, 252, 266, 273, 28, 294, 301, 315, 322, 336, 343, 350, 364, 371, 385, 392, 406, 413, 420, 434, 441, 455, 462, 476, 483, 49, 504, 511, 525, 532, 546

Offset

1,1

Comments

The sequence is a permutation of the positive multiples of 7. - Vladimir Shevelev, May 24 2015

A258334(n) = a(n) / 7 is a permutation of the positive integers. - Reinhard Zumkeller, May 27 2015

Links

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

Éric Angelini, Multiples of 3 ending with n, SeqFan list, May 23 2015.

Mathematica

a[1] = 14; a[n_] := a[n] = For[dn = IntegerDigits[n]; k = 7, True, k = k+7, dk = IntegerDigits[k]; lg = Min[Length[dn], Length[dk]]; If[Union[ Take[dk, lg] - Take[dn, lg]] == {0} && FreeQ[Array[a, n-1], k], Return[k]]]; Array[a, 54] (* Jean-François Alcover, Feb 09 2018 *)

Prog

(Haskell)
import Data.List (isPrefixOf, delete)
a258217 n = a258217_list !! (n-1)
a258217_list = f 1 $ tail $ zip a008589_list $ map show a008589_list where
   f x ws = g ws where
     g ((u, vs) : uvs) = if isPrefixOf (show x) vs
                         then u : f (x + 1) (delete (u, vs) ws) else g uvs

Crossrefs

Cf. A008589, A258188, A258083, A258334.

Sequence in context: A100466 A100467 A082802 * A272470 A094393 A128705

Adjacent sequences: A258214 A258215 A258216 * A258218 A258219 A258220

Keyword

nonn,base,changed

Author

Eric Angelini and Reinhard Zumkeller, May 23 2015

Status

approved