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A004723
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Delete all 4's from the sequence of nonnegative integers.
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9
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0, 1, 2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 1, 15, 16, 17, 18, 19, 20, 21, 22, 23, 2, 25, 26, 27, 28, 29, 30, 31, 32, 33, 3, 35, 36, 37, 38, 39, 0, 1, 2, 3, 5, 6, 7, 8, 9, 50, 51, 52, 53, 5, 55, 56, 57, 58, 59, 60, 61, 62, 63, 6, 65, 66, 67, 68, 69, 70, 71, 72, 73, 7, 75
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internal format)
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OFFSET
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0,3
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COMMENTS
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LINKS
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MAPLE
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f:= proc(n) local L, i;
L:= subs(4=NULL, convert(n, base, 10));
if L = [] then return NULL fi;
add(L[i]*10^(i-1), i=1..nops(L))
end proc:
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PROG
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(MATLAB) m=1;
for u=0:150
v=dec2base(u, 10)-'0'; v = v(v~=4);
if length(v)>0; sol(m)=(str2num(strrep(num2str(v), ' ', ''))); m=m+1; end;
end;
(Python)
l = len(str(n))
m = 4*(10**l-1)//9
k = n + l - int(n+l < m)
return 3 if k == m else int(str(k).replace('4', '')) # Chai Wah Wu, Apr 20 2021
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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