A263487 - OEIS

A263487

Triangle read by rows: T(n,k) (n>=2, k>=0) is the number of permutations of n having a subexpression of maximal defect k.

%I #9 Oct 25 2015 10:54:35

%S 2,5,1,13,7,4,34,33,36,12,4,1

%N Triangle read by rows: T(n,k) (n>=2, k>=0) is the number of permutations of n having a subexpression of maximal defect k.

%C Row sums give A000142, n >= 2.

%H V. V. Deodhar, <a href="http://dx.doi.org/10.1007/BF00181467">A combinatorial setting for questions in Kazhdan-Lusztig theory</a>, Geometriae Dedicata, October 1990, Volume 36, Issue 1, pp 95-119, <a href="http://www.ams.org/mathscinet-getitem?mr=1065215">MR1065215</a>.

%H FindStat - Combinatorial Statistic Finder, <a href="http://www.findstat.org/StatisticsDatabase/St000034">The maximum defect over any reduced expression for a permutation and any subexpression</a>.

%e Triangle begins:

%e 2,

%e 5,1,

%e 13,7,4,

%e 34,33,36,12,4,1,

%e ...

%Y Cf. A000142.

%K nonn,tabf,more

%O 2,1

%A _Christian Stump_, Oct 19 2015