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A073457
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Numbers n such that phi(n) = pi(n) + 2.
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5
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OFFSET
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1,1
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LINKS
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FORMULA
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Solutions to A000010(x)=A000720(x)+k, where k=+2; finite for any fixed value of k.
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EXAMPLE
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8 primes below 22 = {2,3,5,7,11,13,17,19}; 10 terms in RRS[22]={1,3,5,7,9,13,15,17,19,21}, so 22 is here.
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MAPLE
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MATHEMATICA
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Do[s=EulerPhi[n]-PrimePi[n]; If[Equal[s, 2], Print[n]], {n, 10000}]
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PROG
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(Magma) [n: n in [2..1000] | EulerPhi(n) eq #PrimesUpTo(n)+2]; // Vincenzo Librandi, May 10 2015
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CROSSREFS
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KEYWORD
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fini,full,nonn
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AUTHOR
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STATUS
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approved
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