A067386 Primes p such that p+1 and p-1 have the same number of distinct prime factors.

3, 11, 13, 19, 23, 37, 47, 53, 73, 97, 107, 131, 139, 163, 181, 193, 229, 239, 281, 307, 311, 349, 373, 379, 383, 409, 439, 443, 487, 491, 521, 577, 599, 601, 617, 619, 643, 683, 701, 709, 727, 739, 743, 761, 811, 821, 827, 829, 853, 863, 881, 883, 919, 937

Offset

1,1

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Maple

q:= p-> isprime(p) and nops(ifactors(p+1)[2])=nops(ifactors(p-1)[2]):
select(q, [$1..1000])[];  # Alois P. Heinz, May 08 2022

Mathematica

Select[Prime[Range[200]], PrimeNu[#-1]==PrimeNu[#+1]&] (* Harvey P. Dale, Jun 28 2020 *)

Prog

(PARI) is(n)=omega(n-1)==omega(n+1) && isprime(n) \\ Charles R Greathouse IV, Sep 14 2015

Crossrefs

Cf. A115103 (same number of prime factors with multiplicity).

Sequence in context: A338445 A191049 A103835 * A063621 A176870 A089152

Adjacent sequences: A067383 A067384 A067385 * A067387 A067388 A067389

Keyword

easy,nonn

Author

Benoit Cloitre, Feb 23 2002

Status

approved