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A004722 Delete all digits 3 from the terms of the sequence of nonnegative integers.

%I A004722 #49 Apr 22 2021 22:08:57
%S A004722 0,1,2,4,5,6,7,8,9,10,11,12,1,14,15,16,17,18,19,20,21,22,2,24,25,26,
%T A004722 27,28,29,0,1,2,4,5,6,7,8,9,40,41,42,4,44,45,46,47,48,49,50,51,52,5,
%U A004722 54,55,56,57,58,59,60,61,62,6,64,65,66,67,68,69,70,71,72,7,74,75,76
%N A004722 Delete all digits 3 from the terms of the sequence of nonnegative integers.
%C A004722 Very similar to A004178, except that 3-repdigits (A002277) are completely removed from the sequence, whereas A004178 has 0's in their place. It is thus guaranteed that a(n) = n only when n < 3. - _Alonso del Arte_, Oct 18 2012
%H A004722 Alonso del Arte, <a href="/A004722/b004722.txt">Table of n, a(n) for n = 0..9999</a>
%F A004722 a(n) = n for -1 < n < 3;
%F A004722 a(n) = A004178(n + 1) for 2 < n < 32,
%F A004722 a(n) = A004178(n + 2) for 31 < n < 331,
%F A004722 a(n) = A004178(n + 3) for 330 < n < 3330,
%F A004722 a(n) = A004178(n + 4) for 3329 < n < 33329, etc. - _Alonso del Arte_, Oct 21 2012
%t A004722 endAt = 103; Delete[Table[FromDigits[DeleteCases[IntegerDigits[n], 3]], {n, 0, endAt}], Table[{(10^expo - 1)/3 + 1}, {expo, Floor[Log[10, endAt]]}]] (* _Alonso del Arte_, Apr 29 2019 *)
%o A004722 (MATLAB) m=1;
%o A004722 for u=0:1000
%o A004722     v=dec2base(u,10)-'0'; v = v(v~=3);
%o A004722     if length(v)>0;sol(m)=(str2num(strrep(num2str(v), ' ', ''))); m=m+1; end;
%o A004722 end
%o A004722 sol % _Marius A. Burtea_, May 07 2019
%o A004722 (Python)
%o A004722 def A004722(n):
%o A004722     l = len(str(n))
%o A004722     m = (10**l-1)//3
%o A004722     k = n + l - int(n+l < m)
%o A004722     return 2 if k == m else int(str(k).replace('3','')) # _Chai Wah Wu_, Apr 20 2021
%Y A004722 Cf. A004719, A004720, A004721, A004723, A004724, A004725, A004726, A004727, A004728.
%K A004722 base,nonn
%O A004722 0,3
%A A004722 _N. J. A. Sloane_
%E A004722 _Sean A. Irvine_ pointed out erroneous terms in b-file and confirmed correction, Apr 28 2019
%E A004722 Name edited by _Felix Fröhlich_, Apr 29 2019