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%I #17 Jun 14 2016 12:52:39
%S 1,6,3,1,17,33,9,1,40,184,168,27,1,87,792,1592,807,81
%N Irregular triangle read by rows, enumerating permutations of "specification (321^{n-5})".
%C Related to Simon Newcomb's problem.
%C It would be nice to have a more precise definition. See Kaplansky-Riordan, Section 7.
%H Irving Kaplansky and John Riordan, <a href="http://projecteuclid.org/euclid.dmj/1077473616">The problem of the rooks and its applications</a>, Duke Mathematical Journal 13.2 (1946): 259-268.
%H Irving Kaplansky and John Riordan, <a href="/A274105/a274105.pdf">The problem of the rooks and its applications</a>, in Combinatorics, Duke Mathematical Journal, 13.2 (1946): 259-268. [Annotated scanned copy]
%e The triangle starts at row n=5:
%e 1, 6, 3,
%e 1, 17, 33, 9,
%e 1, 40, 184, 168, 27,
%e 1, 87, 792, 1592, 807, 81,
%e ...
%K nonn,tabf,more
%O 5,2
%A _N. J. A. Sloane_, May 07 2016