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A052406 Numbers without 4 as a digit. 12
0, 1, 2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16, 17, 18, 19, 20, 21, 22, 23, 25, 26, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39, 50, 51, 52, 53, 55, 56, 57, 58, 59, 60, 61, 62, 63, 65, 66, 67, 68, 69, 70, 71, 72, 73, 75, 76, 77, 78, 79, 80, 81, 82, 83, 85, 86, 87, 88, 89 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

This is a frequent sequence on Chinese, Japanese and Korean elevator buttons. - Jean-Sebastien Girard (circeus(AT)hotmail.com), Jul 28 2008

Essentially numbers in base 9 (using digits 0, 1, 2, 3, 5, 6, 7, 8, 9 rather than 0-8). - Charles R Greathouse IV, Oct 13 2013

LINKS

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

Eric Weisstein's World of Mathematics, Uban Number

Wikipedia, Tetraphobia.

Index entries for 10-automatic sequences.

FORMULA

a(n) = replace digits d > 3 by d + 1 in base-9 representation of n - 1. - Reinhard Zumkeller, Oct 07 2014

MAPLE

a:= proc(n) local l, m; l, m:= 0, n-1;

      while m>0 do l:= (d->

        `if`(d<4, d, d+1))(irem(m, 9, 'm')), l

      od; parse(cat(l))/10

    end:

seq(a(n), n=1..100);  # Alois P. Heinz, Aug 01 2016

MATHEMATICA

Select[Range[100], DigitCount[#, 10, 4] == 0 &] (* Alonso del Arte, Oct 13 2013 *)

PROG

(PARI) g(n)= local(x, v, j, flag); for(x=1, n, v=Vec(Str(x)); flag=1; for(j=1, length(v), if(v[j]=="4", flag=0)); if(flag, print1(x", ") ) ) \\ Cino Hilliard, Apr 01 2007

(MAGMA) [ n: n in [0..89] | not 4 in Intseq(n) ]; // Bruno Berselli, May 28 2011

(sh) seq 0 1000 | grep -v 4; # Joerg Arndt, May 29 2011

(Haskell)

a052406 = f . subtract 1 where

f 0 = 0

f v = 10 * f w + if r > 3 then r + 1 else r where (w, r) = divMod v 9

-- Reinhard Zumkeller, Oct 07 2014

CROSSREFS

Cf. A004179, A004723, A011760.

Cf. A052382 (without 0), A052383 (without 1), A052404 (without 2), A052405 (without 3), A052413 (without 5), A052414 (without 6), A052419 (without 7), A052421 (without 8), A007095 (without 9).

Sequence in context: A242410 A258022 A089590 * A022306 A183298 A081023

Adjacent sequences:  A052403 A052404 A052405 * A052407 A052408 A052409

KEYWORD

base,easy,nonn

AUTHOR

Henry Bottomley, Mar 13 2000

EXTENSIONS

Offset changed by Reinhard Zumkeller, Oct 07 2014

STATUS

approved

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Last modified January 20 14:40 EST 2019. Contains 319333 sequences. (Running on oeis4.)