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Search: id:A078330
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| A078330 |
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Primes p such that mu(p-1) = -1; that is, p-1 is square-free and has an odd number of prime factors, where mu is the Moebius function. |
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+0
5
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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
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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Eric Weisstein's World of Mathematics, Moebius Function
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EXAMPLE
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31 is in the sequence because 31 is a prime and mu(30)=-1.
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MATHEMATICA
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Select[Prime[Range[400]], MoebiusMu[ #-1]==-1&] (from T. D. Noe)
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PROGRAM
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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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Cf. A049092 (primes p with mu(p-1)=0), A088179 (primes p with mu(p-1)=1), A089451 (mu(p-1) for prime p).
Sequence in context: A045709 A090151 A068331 this_sequence A107210 A119739 A163579
Adjacent sequences: A078327 A078328 A078329 this_sequence A078331 A078332 A078333
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KEYWORD
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easy,nonn
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AUTHOR
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Shyam Sunder Gupta (guptass(AT)rediffmail.com), Nov 21 2002
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