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A163561
Composite numbers such that exactly nine distinct permutations of digits give primes.
3
1094, 1349, 1394, 1457, 1475, 1490, 1547, 1574, 1745, 1754, 1904, 1934, 1940, 1943, 3097, 3149, 3194, 3419, 3479, 3497, 3679, 3749, 3790, 3794, 3796, 3914, 3941, 3970, 3974, 3976, 4109, 4175, 4190, 4193, 4319, 4379, 4571, 4715, 4739, 4901, 4910, 4913
OFFSET
1,1
EXAMPLE
a(1) = 1094 because 1094 is composite, the nine permutations 149, 419, 491, 941, 1049, 1409, 4019, 4091, and 9041 are all prime, and no other permutation of 1094 is prime.
CROSSREFS
Sequence in context: A022197 A259909 A124122 * A203807 A184470 A234722
KEYWORD
easy,nonn,base
AUTHOR
Gil Broussard, Jul 30 2009
STATUS
approved