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A066325 Coefficients of unitary Hermite polynomials He_n(x). 7
1, 0, 1, -1, 0, 1, 0, -3, 0, 1, 3, 0, -6, 0, 1, 0, 15, 0, -10, 0, 1, -15, 0, 45, 0, -15, 0, 1, 0, -105, 0, 105, 0, -21, 0, 1, 105, 0, -420, 0, 210, 0, -28, 0, 1, 0, 945, 0, -1260, 0, 378, 0, -36, 0, 1, -945, 0, 4725, 0, -3150, 0, 630, 0, -45, 0, 1, 0, -10395, 0, 17325, 0 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,8

COMMENTS

Also number of involutions on n labeled elements with k fixed points times (-1)^(number of 2-cycles).

Also called normalized Hermite polynomials.

REFERENCES

F. Bergeron, G. Labelle and P. Leroux, Combinatorial Species and Tree-Like Structures, Cambridge, 1998, pg 89,94 (2.3.41,54).

LINKS

Table of n, a(n) for n=0..70.

P. Diaconis and A. Gamburd, Random matrices, magic squares and matching polynomials, The Electronic Journal of Combinatorics, Volume 11, Issue 2 (2004-6), Research Paper #R2.

E. Elizalde, Cosmology: techniques and observations, arXiv:gr-qc/0409076, 2004.

D. Foata, Une méthode combinatoire pour l'étude des fonctions spéciales

Index entries for sequences related to Hermite polynomials

FORMULA

T(n, k)=(-2)^((k-n)/2)*n!/(k!*((n-k)/2)!). n-k even. 0 otherwise.

E.g.f. (relative to x): A(x, y) = exp(x*y-x^2/2).

The umbral compositional inverses (Cf. A001147) of the polynomials He(n,x) are given by the same polynomials unsigned, A099174 . - Tom Copeland, Nov 15 2014

EXAMPLE

1;

0,  1;

-1, 0,  1;

0, -3,  0, 1;

3,  0, -6, 0, 1;

...

MATHEMATICA

H[0, x_] = 1; H[1, x_] := x; H[n_, x_] := H[n, x] = x*H[n-1, x] - (n-1)*H[n-2, x] // Expand; Table[CoefficientList[H[n, x], x], {n, 0, 11}] // Flatten (* Jean-François Alcover, May 11 2015 *)

PROG

(Sage)

def A066325_row(n):

    T = [0]*(n+1)

    if n==1: return [1]

    for m in (1..n-1):

        a, b, c = 1, 0, 0

        for k in range(m, -1, -1):

            r = a - (k+1)*c

            if k < m : T[k+2] = u;

            a, b, c = T[k-1], a, b

            u = r

        T[1] = u;

    return T[1:]

for n in (1..11): A066325_row(n)  # Peter Luschny, Nov 01 2012

CROSSREFS

Row sums: A001464 (with different signs). Row sums of absolute values: A000085.

Cf. A060281.

Absolute values are given in A099174. - M. F. Hasler, Oct 08 2012

Cf. A001147.

Sequence in context: A247622 A256037 A179898 * A099174 A137297 A178117

Adjacent sequences:  A066322 A066323 A066324 * A066326 A066327 A066328

KEYWORD

sign,tabl

AUTHOR

Christian G. Bower, Dec 14 2001

STATUS

approved

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Last modified September 2 14:56 EDT 2015. Contains 261284 sequences.