

A007976


Generalized Euler numbers O_n^+(2).


0




OFFSET

1,2


COMMENTS

"The numerical computations for small n in the simplest case q = 2 lead to the remarkable observations: the sequence {O_n^+(2)} is very close to the sequence ... of ... Euler numbers [A000111]." {Kirollov, 1995, page 52]


REFERENCES

A. A. Kirillov, Variations on the triangular theme, Amer. Math. Soc. Transl., (2), Vol. 169, 1995, pp. 4373, see p. 52.


LINKS

Table of n, a(n) for n=1..9.
Marcelo Aguiar, Nantel Bergeron and Nathaniel Thiem, Hopf monoids from class functions on unitriangular matrices, arXiv preprint arXiv:1203.1572 [math.CO], 2012.  From N. J. A. Sloane, Sep 14 2012
A. A. Kirillov, On the combinatorics of coadjoint orbits, Funct. Anal. Applic., vol. 27 1992 pages 6264.


EXAMPLE

a(7) is the number of conjugacy classes in a Borel subgroup of GL(7,2), also the number of complex irreducible representations and is easily computed by GAP to be 1430.  Dmitrii Pasechnik, Mar 27 2008


CROSSREFS

Cf. A000111.
Sequence in context: A275711 A163747 A000111 * A058259 A033543 A124531
Adjacent sequences: A007973 A007974 A007975 * A007977 A007978 A007979


KEYWORD

nonn,more


AUTHOR

Alexandre Kirillov (kirillov(AT)math.upenn.edu)


EXTENSIONS

a(7) corrected by Dmitrii Pasechnik, Mar 27 2008


STATUS

approved



