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 A166257 #14 Jan 31 2025 09:25:12
%S A166257 1,7,11,15,17,19,23,27,29,31,35,39,41,43,47,49,51,53,55,59,63,65,67,
%T A166257 69,71,75,77,79,83,87,89,91,95,97,99,101,103,107,109,111,113,115,119,
%U A166257 123,125,127,129,131,135,137,139,143,147,149,151,153,155,159,161,163,167
%N A166257 Odd numbers not of the form prime(k) + phi(prime(k)).
%H A166257 Harvey P. Dale, <a href="/A166257/b166257.txt">Table of n, a(n) for n = 1..1000</a>
%F A166257 {1} U {A005408 \ A076274 }. - _R. J. Mathar_, May 21 2010
%p A166257 L := 100; S := {}:
%p A166257 for i from 2 to L do
%p A166257 for j from 2 to L do
%p A166257 if i*j <= L then S := `union`(S, {2*i*j-1}) end if;
%p A166257 end do;
%p A166257 end do:
%p A166257 {1} union S; # _Peter Bala_, Jan 30 2025
%t A166257 Module[{upto=200},Complement[Range[1,upto,2],Table[n+EulerPhi[n],{n,Prime[ Range[PrimePi[upto]]]}]]] (* _Harvey P. Dale_, Jun 21 2019 *)
%Y A166257 Cf. A000010, A000040, A005408.
%K A166257 nonn,easy
%O A166257 1,2
%A A166257 _Juri-Stepan Gerasimov_, Oct 10 2009
%E A166257 Entries checked by _R. J. Mathar_, May 21 2010.