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 A063742 #20 Jun 02 2025 08:36:14
%S A063742 0,1,2,3,4,5,6,7,8,9,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,27,
%T A063742 28,29,30,31,32,33,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,51,53,
%U A063742 54,55,56,57,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78
%N A063742 Cototients: numbers k such that x - phi(x) = k has at least one solution.
%C A063742 Numbers in range of A051953, the cototients. Complement of non-cototients, A005278 with respect to natural numbers A000027.
%H A063742 Amiram Eldar, <a href="/A063742/b063742.txt">Table of n, a(n) for n = 1..10000</a>
%e A063742 First missing numbers are: 10,26,34,50,52,... These missing values are collected in A005278.
%t A063742 Union[Table[w-EulerPhi[w], {w, 1, A}]] (* taken for sufficiently large A. *)
%Y A063742 Cf. A000010, A005278, A051953, A083533, A083534, A083536.
%Y A063742 Analogous to A002202.
%K A063742 nonn
%O A063742 1,3
%A A063742 _Labos Elemer_, Aug 13 2001, corrected May 20 2003
%E A063742 Edited by _N. J. A. Sloane_, Nov 17 2008 at the suggestion of _R. J. Mathar_