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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. 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.)