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A220627 Prime numbers that are not Brazilian. 6
2, 3, 5, 11, 17, 19, 23, 29, 37, 41, 47, 53, 59, 61, 67, 71, 79, 83, 89, 97, 101, 103, 107, 109, 113, 131, 137, 139, 149, 151, 163, 167, 173, 179, 181, 191, 193, 197, 199, 223, 227, 229, 233, 239, 251, 257, 263, 269, 271, 277, 281, 283, 293, 311, 313, 317 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

These are primes not in A085104 (Brazilian primes).

Primes that are not repunit in 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 xrange(2, n - 1):

        d=digits(n, b)[1:]

        if max(d)==min(d): l+=[n, ]

    return l

def ok(n): return 1 if len(B(n))==0 else 0

print [n for n in primerange(2, 1001) if ok(n)] # Indranil Ghosh, Jun 22 2017

CROSSREFS

Sequence in context: A044042 A175179 A040060 * A040083 A045308 A245639

Adjacent sequences:  A220624 A220625 A220626 * A220628 A220629 A220630

KEYWORD

nonn,base,changed

AUTHOR

Bernard Schott, Dec 17 2012

STATUS

approved

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Last modified June 27 07:55 EDT 2017. Contains 288777 sequences.