%I A078431
%S A078431 0,1,1,3,3,20,126,694,2874,25059
%N A078431 Number of permutations p of 1,2,...,n such that both numerator and denominator 
               of the continued fraction [p(1); p(2),...,p(n)] are primes.
%C A078431 Based on a question from Leroy Quet.
%H A078431 Leroy Quet, <a href="http://www.prism-of-spirals.net/">Home Page</a> 
               (listed in lieu of email address)
%e A078431 a(4)=3 because [2;1,3,4]=47/17, [2;3,1,4]=43/19, [4;3,1,2]=47/11
%Y A078431 Cf. A078432, A078433.
%Y A078431 Sequence in context: A157050 A059368 A090694 this_sequence A112534 A006656 
               A159910
%Y A078431 Adjacent sequences: A078428 A078429 A078430 this_sequence A078432 A078433 
               A078434
%K A078431 more,nonn
%O A078431 1,4
%A A078431 Reiner Martin (reinermartin(AT)hotmail.com), Dec 30 2002