A224240 Number of rationally smooth Schubert varieties of type B_n.

1, 8, 34, 142, 596, 2530, 10842, 46766, 202594, 880210

Offset

1,2

Comments

Also, the number of signed permutations w in the hyperoctahedral group whose initial interval [id,w] in Bruhat order is rank symmetric. Equivalently, the Kazhdan-Lusztig polynomial P_id,w(q) = 1. Characterized by pattern avoidance.

References

S. Billey, Pattern avoidance and rational smoothness of Schubert varieties, Advances in Math, vol. 139 (1998) pp. 141-156.

Links

Table of n, a(n) for n=1..10.

Crossrefs

Cf. A061539.

Sequence in context: A302083 A124843 A082840 * A101644 A126395 A335749

Adjacent sequences: A224237 A224238 A224239 * A224241 A224242 A224243

Keyword

nonn,hard,more

Author

Sara Billey, Apr 01 2013

Status

approved