OFFSET
1,1
COMMENTS
These are primes not in A085104 (Brazilian primes).
Primes that are not repunit in any base b >= 2 with three or more digits.
LINKS
T. D. Noe, Table of n, a(n) for n = 1..1000
Bernard Schott, Les nombres brésiliens, Quadrature, no. 76, avril-juin 2010, pages 30-38; included here with permission from the editors of Quadrature.
MATHEMATICA
brazBases[n_] := Select[Range[2, n - 2], Length[Union[IntegerDigits[n, #]]] == 1 &]; Select[Range[2, 1000], PrimeQ[#] && brazBases[#] == {} &] (* T. D. Noe, Dec 26 2012 *)
PROG
(Python)
from sympy.ntheory.factor_ import digits
from sympy import isprime, primerange
def B(n):
l=[]
for b in range(2, n - 1):
d=digits(n, b)[1:]
if max(d)==min(d): l.append(n)
return l
print([n for n in primerange(2, 1001) if not B(n)]) # Indranil Ghosh, Jun 22 2017
(PARI) isok(p) = {if (isprime(p), for (b=2, p-1, my(d=digits(p, b), md=vecmin(d)); if ((#d > 2) && (md == 1) && (vecmax(d) == 1), return (0)); ); return (1); ); } \\ Michel Marcus, Apr 30 2021
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Bernard Schott, Dec 17 2012
STATUS
approved