A004723 Delete all 4's from the sequence of nonnegative integers.

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

Offset

0,3

Comments

Differs from A004179 where A004179(4) = A004179(44) = A004179(444) = ... = 0. - Michel Marcus, May 17 2019

Links

Robert Israel, Table of n, a(n) for n = 0..10000

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.

Cf. A004719, A004720, A004721, A004722, A004724, A004725, A004726, A004727, A004728.

Sequence in context: A019517 A031976 A023839 * A293754 A242410 A258022

Adjacent sequences: A004720 A004721 A004722 * A004724 A004725 A004726

Keyword

base,nonn,look

Author

N. J. A. Sloane

Status

approved