This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A004178 #14 Oct 24 2023 20:39:04
%S A004178 0,1,2,0,4,5,6,7,8,9,10,11,12,1,14,15,16,17,18,19,20,21,22,2,24,25,26,
%T A004178 27,28,29,0,1,2,0,4,5,6,7,8,9,40,41,42,4,44,45,46,47,48,49,50,51,52,5,
%U A004178 54,55,56,57,58,59,60,61,62,6,64,65,66,67,68,69,70,71,72,7,74
%N A004178 Omit 3's from n.
%C A004178 a(n) = 0 when n = 0 or when n is a 3-repdigit (A002277). a(n) = n when it contains no 3 among its digits. - _Alonso del Arte_, Oct 16 2012
%e A004178 a(13) = 1 because after deleting the 3 from its base 10 representation, we're left with 1.
%e A004178 a(14) = 14 because there are no 3s to delete.
%t A004178 Table[FromDigits[DeleteCases[IntegerDigits[n], 3]], {n, 0, 74}] (* _Alonso del Arte_, Oct 16 2012 *)
%o A004178 (PARI) a(n)=subst(Pol(select(k->k-3,digits(n))),'x,10) \\ _Charles R Greathouse IV_, Oct 16 2012
%Y A004178 Cf. A004722, A052405.
%K A004178 nonn,base,easy
%O A004178 0,3
%A A004178 _N. J. A. Sloane_