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A020458
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Primes that contain digits 2 and 3 only.
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52
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2, 3, 23, 223, 233, 2333, 3323, 23333, 32233, 32323, 33223, 222323, 232333, 233323, 323233, 323333, 333233, 333323, 2222333, 2223233, 2232323, 2233223, 2332333, 2333323, 3222223, 3223223, 3223333, 3233323, 3233333, 3332233, 3333233, 22222223, 22223323, 22232233
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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Flatten[Table[Select[FromDigits/@Tuples[{2, 3}, n], PrimeQ], {n, 7}]] (* Harvey P. Dale, Jul 13 2012 *)
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PROG
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(PARI) go(n)=my(v=List([2]), x, t); for(d=1, n, x=10^d\9*2; forstep(i=1, 2^d-1, 2, if(ispseudoprime(t=x+fromdigits(binary(i))), listput(v, t)))); Vec(v) \\ Charles R Greathouse IV, Sep 14 2015
(Python)
from sympy import isprime
from itertools import count, islice, product
def agen(): # generator of terms
yield from [2, 3]
for d in count(2):
for first in product("23", repeat=d-1):
t = int("".join(first) + "3")
if isprime(t): yield t
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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Edited by N. J. A. Sloane, Jul 27 2008 at the suggestion of Dmitry Kamenetsky.
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STATUS
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approved
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