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 A088179 Primes p such that mu(p-1) = 1; that is, p-1 is squarefree and has an even number of prime factors, where mu is the Moebius function. 9
 2, 7, 11, 23, 47, 59, 83, 107, 167, 179, 211, 227, 263, 331, 347, 359, 383, 463, 467, 479, 503, 547, 563, 571, 587, 691, 719, 839, 859, 863, 887, 911, 967, 983, 1019, 1123, 1187, 1231, 1283, 1291, 1303, 1307, 1319, 1327, 1367, 1439, 1483, 1487, 1523, 1619, 1723 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS It is an unsolved problem to determine if this sequence has a positive density in the primes. - Pieter Moree (moree(AT)mpim-bonn.mpg.de), Nov 03 2003 Except for the initial element 2, this sequence seems to be exactly those primes the sum of whose nonquadratic, nonprimitive-root residues is congruent to -1(mod p). - Dimitri Papadopoulos, Jan 10 2016 LINKS Robert Israel, Table of n, a(n) for n = 1..10000 Eric Weisstein's World of Mathematics, Moebius Function MAPLE filter:= proc(p) isprime(p) and numtheory:-mobius(p-1) = 1 end proc: select(filter, [2, seq(i, i=3..2000, 2)]); # Robert Israel, Feb 03 2016 MATHEMATICA Select[Prime[Range[400]], MoebiusMu[ #-1]==1&] PROG (PARI) lista(nn) = forprime(p=2, nn, if (moebius(p-1) == 1, print1(p, ", "))); \\ Michel Marcus, Jan 10 2016 (PARI) list(lim)=my(v=List(), last); forsquarefree(k=1, lim\1, if(moebius(k)==1, last=k[1], if(k[2][, 2]==[1]~ && k[1]-last==1, listput(v, k[1])))); Vec(v) \\ Charles R Greathouse IV, Jan 08 2018 (MAGMA) [n: n in [2..2000] | IsPrime(n) and MoebiusMu(n-1) eq 1]; // Vincenzo Librandi, Jan 10 2016 CROSSREFS Cf. A049092 (primes p with mu(p-1)=0), A078330 (primes p with mu(p-1)=-1), A089451 (mu(p-1) for prime p). Cf. A002496. Sequence in context: A329309 A217304 A179876 * A228434 A031873 A075356 Adjacent sequences:  A088176 A088177 A088178 * A088180 A088181 A088182 KEYWORD nonn AUTHOR N. J. A. Sloane and T. D. Noe, Nov 03 2003 STATUS approved

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Last modified April 11 00:03 EDT 2021. Contains 342877 sequences. (Running on oeis4.)