A268936 Number of sequences in {1,...,n}^n with longest increasing subsequence of length n-2.
0, 0, 0, 10, 175, 1131, 4501, 13588, 34245, 75925, 152911, 285726, 502723, 841855, 1352625, 2098216, 3157801, 4629033, 6630715, 9305650, 12823671, 17384851, 23222893, 30608700, 39854125, 51315901, 65399751, 82564678, 103327435, 128267175, 158030281, 193335376
Offset: 0
Examples
a(3) = 10: 111, 211, 221, 222, 311, 321, 322, 331, 332, 333. a(4) = 175: 1112, 1113, 1114, 1121, ..., 4414, 4423, 4424, 4434.
Links
- Alois P. Heinz, Table of n, a(n) for n = 0..1000
Crossrefs
A diagonal of A245667.
Formula
G.f.: x^3*(3*x^6-20*x^5+57*x^4-91*x^3+116*x^2+105*x+10)/(1-x)^7.