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%I #10 Oct 23 2024 18:10:48
%S 1,5,36,48,84
%N Numbers n such that phi(n) = pi(n)+1.
%F Solutions to A000010(x)=A000720(x)+k, where k=+1; finite for any fixed value of k.
%e 15 primes below 48 = {2,3,5,7,11,13,17,19,23,29,31,37,41,43,47}; 16 terms in RRS[48]={1,5,7,11,13,17,19,23,25,29,31,35,37,41,43,47}, so 48 is here.
%t Do[s=EulerPhi[n]-PrimePi[n]; If[Equal[s, 1], Print[n]], {n, 1, 10000}]
%t Select[Range[100],EulerPhi[#]==PrimePi[#]+1&] (* _Harvey P. Dale_, Oct 23 2024 *)
%Y Cf. A037228, A037171, A000010, A000720, A073455.
%K fini,full,nonn
%O 1,2
%A _Labos Elemer_, Aug 02 2002
%E Definition modified by _Harvey P. Dale_, Oct 23 2024