

A337871


Primes p such that if the decimal representation of p is interpreted in base q, where q is the prime before p, the result is prime.


2



23, 41, 43, 47, 67, 89, 157, 197, 199, 317, 337, 409, 461, 641, 683, 773, 937, 971, 991, 1231, 1303, 1321, 1453, 1619, 1789, 1877, 2003, 2089, 2113, 2153, 2203, 2243, 2311, 2339, 2351, 2579, 2683, 2917, 2971, 2999, 3019, 3613, 3709, 4241, 4261, 4357, 4481, 4591, 4603, 4663, 5059, 5527, 5741, 6221
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OFFSET

1,1


COMMENTS

3, 5 and 7 are not included because they are not legal digits in bases 2, 3 and 5.


LINKS

Robert Israel, Table of n, a(n) for n = 1..10000


EXAMPLE

a(3)=43 is included because 43 is prime, the previous prime is 41, and 43_41=167 is prime.


MAPLE

R:= NULL: count:= 0:
p:= 11:
while count < 100 do
q:= p; p:= nextprime(p);
L:= convert(p, base, 10);
x:= add(L[i]*q^(i1), i=1..nops(L));
if isprime(x) then count:= count+1; R:= R, p;
fi
od:
R;


CROSSREFS

Cf. A337872.
Sequence in context: A345277 A209985 A244323 * A227174 A050657 A050668
Adjacent sequences: A337868 A337869 A337870 * A337872 A337873 A337874


KEYWORD

nonn,base


AUTHOR

J. M. Bergot and Robert Israel, Sep 27 2020


STATUS

approved



