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 A221178 #17 Jun 07 2016 10:36:19
%S A221178 0,1,2,3,4,6,7,8,10,12,15,16,18,20,22,24,26,28,30,31,32,36,40,42,44,
%T A221178 46,48,52,54,56,58,60,63,64,66,70,72,78,80,82,84,88,92,96,100,102,104,
%U A221178 106,108,110,112,116,120,124,126,127,128,130,132,136,138,140,144,148,150,156,160,162,164,166,168,172,176
%N A221178 Union of (prime powers minus 1) and values of Euler totient function.
%F A221178 Union of A181062 and A002202.
%t A221178 max = 200;
%t A221178 selNu = Select[Range[max], PrimeNu[#] == 1&]-1;
%t A221178 phiQ[m_] := Select[Range[m+1, 2*m*Product[1/(1-1/(k*Log[k])), {k, 2, DivisorSigma[0, m]}]], EulerPhi[#] == m&, 1] != {};
%t A221178 selPhi = Select[Range[max], phiQ];
%t A221178 Join[{0}, Union[selNu, selPhi]]
%o A221178 (PARI) list(lim)=my(P=1, q, v, u=List([0])); forprime(p=2, default(primelimit), if(eulerphi(P*=p)>=lim, q=p; break)); v=vecsort(vector(P/q*lim\eulerphi(P/q), k, eulerphi(k)), , 8); v=select(n->n<=lim, v); forprime(p=2,sqrtint(lim\1+1),P=p;while((P*=p) <= lim+1, listput(u, P-1))); vecsort(concat(v, Vec(u)),,8) \\ _Charles R Greathouse IV_, Jan 08 2013
%Y A221178 Cf. A000010, A002202, A000961, A181062, A070932 (multiplicative closure).
%K A221178 nonn
%O A221178 1,3
%A A221178 _Jean-François Alcover_, Jan 06 2013
%E A221178 Edited by _N. J. A. Sloane_, Jan 06 2013