1,2

Paul Tek, Table of n, a(n) for n = 1..10000

11 follows 20 as the smallest number not included earlier and differing at every digit position.

(Haskell)

import Data.List (delete)

a068861 n = a068861_list !! (n-1)

a068861_list = f "x" (map show [1..]) where

f u us = g us where

g (v:vs)

| and $ zipWith (/=) u v = (read v :: Int) : f v (delete v us)

| otherwise = g vs

-- Reinhard Zumkeller, Dec 21 2013

Cf. A068860, A068863.

Cf. A067581.

Sequence in context: A223080 A248651 A306361 * A256079 A216556 A068860

Adjacent sequences: A068858 A068859 A068860 * A068862 A068863 A068864

nonn,base

Amarnath Murthy, Mar 13 2002

approved