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A004723 Delete all 4's from the sequence of nonnegative integers. 9
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
COMMENTS
Differs from A004179 where A004179(4) = A004179(44) = A004179(444) = ... = 0. - Michel Marcus, May 17 2019
LINKS
MAPLE
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:
map(f, [$0..100]); # Robert Israel, May 17 2019
PROG
(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;
sol % Marius A. Burtea, May 17 2019
(Python)
def A004723(n):
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
CROSSREFS
Cf. A004179.
Sequence in context: A019517 A031976 A023839 * A293754 A242410 A258022
KEYWORD
base,nonn,look
AUTHOR
STATUS
approved

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Last modified March 19 01:57 EDT 2024. Contains 370952 sequences. (Running on oeis4.)