9851
This number is a prime.
Prime 9851 is a prime p with this property: the
concatenations pq and qp are both primes, where q is the
next prime after p. The next prime after 9851 is 9857 and
both 98519857 and 98579851 are prime. There are 22 primes
like this less than 10000 and 9851 is the largest one. [Keith]
Number of tilings of a 6 x 4 rectangle using pentominoes of
shapes L, U, X and monominoes. [Heinz]
Printed from the PrimePages <t5k.org> © G. L. Honaker and Chris K. Caldwell