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 A227623 #20 Jul 04 2017 18:48:16 %S A227623 2,5,6,17,18,23,24,25,31,33,36,41,47,48,51,70,75,84,87,98,106,109,111, %T A227623 127,130,157,160,170,180,191,192,197,211,212,217,219,220,221,233,236, %U A227623 241,242,244,247,248,257,258,259,260,261,278,279,286,288,290,331,333 %N A227623 Numbers n such that phi(n) + pi(n) is prime. %H A227623 K. D. Bajpai, <a href="/A227623/b227623.txt">Table of n, a(n) for n = 1..1326</a> %e A227623 phi(786) + pi(786) = 260 + 137 = 397 which is prime, so 786 is in the sequence. %p A227623 with(numtheory):K := proc(n) local a; a :=(phi(n)+ pi(n)); if isprime(a) then RETURN (n) fi: end: seq(K(n), n=1..1000); # _K. D. Bajpai_, Jul 18 2013 %p A227623 with(numtheory):K:=proc()local n,a,c; c:=1; for n from 1 to 10000 do; a:=(phi(n)+ pi(n));if isprime(a) then lprint(c,n); c:=c+1; fi;od; end: K(); # _K. D. Bajpai_, Jul 18 2013 %t A227623 Select[Range[200], PrimeQ[EulerPhi[#] + PrimePi[#]] &] (* _G. C. Greubel_, Jul 04 2017 *) %Y A227623 Cf. A097646. %K A227623 nonn,less %O A227623 1,1 %A A227623 _K. D. Bajpai_, Jul 18 2013