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 A057859 #14 May 13 2017 21:05:07
%S A057859 1,2,3,3,5,4,7,5,7,6,11,6,13,8,10,9,17,8,19,10,14,12,23,10,21,14,19,
%T A057859 14,29,11,31,17,22,18,26,14,37,20,26,18,41,15,43,22,26,24,47,18,43,22,
%U A057859 34,26,53,20,42,26,38,30,59,19,61,32,38,33,50,23,67,34,46
%N A057859 Number of residue classes modulo n which contain a prime.
%C A057859 a(n) = n iff n is prime; a(2*n)<=n+1; a(4*p)=2*p for primes p>2: a(A001749(n))=A057860(A001749(n)). - _Reinhard Zumkeller_, Jan 11 2004
%H A057859 Alois P. Heinz, <a href="/A057859/b057859.txt">Table of n, a(n) for n = 1..10000</a>
%F A057859 a(n) = A000010(n) + A001221(n) = n - A057860(n).
%e A057859 a(30) = 11 since 30k+m can be prime if m = 2, 3 or 5 (once each with k = 0) or m = 1, 7, 11, 13, 17, 19, 23 or 29 (each for an infinite number of values of k).
%p A057859 with(numtheory):
%p A057859 a:= n-> phi(n)+nops(factorset(n)):
%p A057859 seq(a(n), n=1..100); # _Alois P. Heinz_, Jul 14 2016
%t A057859 Table[EulerPhi[n] + PrimeNu[n], {n, 1, 100}] (* _G. C. Greubel_, May 13 2017 *)
%o A057859 (PARI) for(n=1,100, print1(eulerphi(n) + omega(n), ", ")) \\ _G. C. Greubel_, May 13 2017
%Y A057859 Cf. A057857, A179179.
%K A057859 nonn,look
%O A057859 1,2
%A A057859 _Henry Bottomley_, Sep 08 2000