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A073456
Numbers n such that phi(n) = pi(n)+1.
3
1, 5, 36, 48, 84
OFFSET
1,2
FORMULA
Solutions to A000010(x)=A000720(x)+k, where k=+1; finite for any fixed value of k.
EXAMPLE
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.
MATHEMATICA
Do[s=EulerPhi[n]-PrimePi[n]; If[Equal[s, 1], Print[n]], {n, 1, 10000}]
Select[Range[100], EulerPhi[#]==PrimePi[#]+1&] (* Harvey P. Dale, Oct 23 2024 *)
CROSSREFS
KEYWORD
fini,full,nonn
AUTHOR
Labos Elemer, Aug 02 2002
EXTENSIONS
Definition modified by Harvey P. Dale, Oct 23 2024
STATUS
approved