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A078330 Primes p such that mu(p-1) = -1; that is, p-1 is squarefree and has an odd number of prime factors, where mu is the Moebius function. 7
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; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..50.

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. 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

Adjacent sequences:  A078327 A078328 A078329 * A078331 A078332 A078333

KEYWORD

easy,nonn

AUTHOR

Shyam Sunder Gupta, Nov 21 2002

STATUS

approved

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Last modified January 20 10:38 EST 2018. Contains 297960 sequences.