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A078330
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Primes p such that mu(p-1) = -1, where mu is the Moebius function; that is, p-1 is squarefree and has an odd number of prime factors.
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10
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3, 31, 43, 67, 71, 79, 103, 131, 139, 191, 223, 239, 283, 311, 367, 419, 431, 439, 443, 499, 599, 607, 619, 643, 647, 659, 683, 743, 787, 823, 827, 907, 947, 971, 1031, 1039, 1087, 1091, 1103, 1163, 1223, 1259, 1399, 1427, 1447, 1499, 1511, 1543, 1559, 1571
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OFFSET
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1,1
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LINKS
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EXAMPLE
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31 is in the sequence because 31 is a prime and mu(30) = -1.
37 is not in the sequence because, although 37 is prime, mu(36) = 0.
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MATHEMATICA
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Select[Prime[Range[400]], MoebiusMu[# - 1] == -1 &] (* from T. D. Noe *)
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PROG
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(PARI) j=[]; forprime(n=1, 2000, if(moebius(n)==moebius(n-1), j=concat(j, n))); j
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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