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A078330
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.
10
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
OFFSET
1,1
LINKS
Eric Weisstein's World of Mathematics, Moebius Function.
EXAMPLE
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.
MATHEMATICA
Select[Prime[Range[400]], MoebiusMu[# - 1] == -1 &] (* from T. D. Noe *)
PROG
(PARI) j=[]; forprime(n=1, 2000, if(moebius(n)==moebius(n-1), j=concat(j, n))); j
CROSSREFS
Cf. A008683, 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: A211003 A068331 A177104 * A107210 A256473 A119739
KEYWORD
easy,nonn
AUTHOR
Shyam Sunder Gupta, Nov 21 2002
STATUS
approved