

A316479


a(n) is the smallest prime whose baseb expansion, read as a base10 number, is a prime for every b in 2, 3, ..., n. (For n > 10, each baseb expansion for 10 < b <= n must contain no digit larger than 9.)


0




OFFSET

2,1


COMMENTS

a(2)=3, the smallest term in A065720, primes whose binary representation is also the decimal representation of a prime;
a(3)=157, the smallest integer in both A065720 and A065721, primes p whose base3 expansion is also the decimal expansion of a prime;
Is this sequence infinite?


LINKS



EXAMPLE

a(2)=3 because 3 is prime, 3_10 = 11_2, and 11 is prime, and 3 is the smallest such number.
a(3)=157 because 157 is prime, 157_10 = 10011101_2, 157_10 = 12211_3, and 10011101 and 12211 are prime, and 157 is the smallest such number. a(4)=157 as well, since 157_10 = 2131_4 and 2131 is also prime.


CROSSREFS



KEYWORD

nonn,base,more


AUTHOR



EXTENSIONS



STATUS

approved



