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A066072
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Prime numbers arising in A066071.
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10
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2, 3, 3, 5, 7, 5, 5, 7, 7, 13, 11, 13, 19, 13, 17, 17, 13, 19, 17, 13, 23, 17, 43, 19, 41, 37, 29, 17, 31, 37, 37, 41, 37, 61, 41, 43, 41, 73, 61, 47, 73, 43, 61, 41, 53, 37, 41, 73, 37, 89, 73, 59, 97, 61, 61, 101, 37, 41, 109, 67, 73, 71, 113, 73, 73, 41, 73, 97, 61, 79, 83
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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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EXAMPLE
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Solutions to 1+phi(x)=13 are {13, 21, 26, 28, 36, 42}; so 13 occur 5 times in the sequence in positions 10, 13, 15, 18 and 21, obtained as 1+Phi[m] values for 5 composite arguments.
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MATHEMATICA
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Select[EulerPhi@ # + 1 & /@ Complement[Range@ #, Prime@ Range@ PrimePi@ #] &@ 168, PrimeQ] (* Michael De Vlieger, Jul 01 2016 *)
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PROG
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(PARI) { n=0; for (m=1, 10^9, if (!isprime(m) && isprime(p=(eulerphi(m) + 1)), write("b066072.txt", n++, " ", p); if (n==1000, return)) ) } \\ Harry J. Smith, Nov 10 2009
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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