568504

Appears in sequences

• Number of self-inverse permutations on n letters, also known as involutions; number of standard Young tableaux with n cells.at n=13A000085
• Bisection of A000085.at n=6A066224
• Number of 13 X 13 arrays of squares of integers, symmetric about main diagonal, with all rows summing to n.at n=1A156412
• Number T(n,k) of sets of exactly k nonempty words with a total of n letters over n-ary alphabet such that within each prefix of a word every letter of the alphabet is at least as frequent as the subsequent alphabet letter; triangle T(n,k), n>=0, read by rows.at n=51A293815
• Number T(n,k) of partitions of [n] having exactly k blocks of size at least three; triangle T(n,k), n>=0, 0<=k<=floor(n/3), read by rows.at n=35A355144
• Number of involutions in the symmetric group S_n with at least one fixed point.at n=13A378100