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A291879 Number of monomials of the Schubert polynomial of the permutation 351624 tensor 1^n. 1
1, 8, 6720, 561120560, 4557185891241984, 3571558033324129373292768, 269111599998006391761541640176800000, 1945556482213500279178010210766074095827609600000, 1347912754604769492992184400055703948513202427323999206349209600 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

The permutation 351624 tensor 1^n is the permutation whose permutation matrix is obtained from that of 351624 by replacing each 1 with an n X n identity matrix.

LINKS

Table of n, a(n) for n=0..8.

A. H. Morales, I. Pak, G. Panova, Hook formulas for skew shapes III. Multivariate and product formulas, arXiv:1707.00931 [math.CO], 2017.

R. P. Stanley, Some Schubert shenanigans, arXiv:1704.00851 [math.CO], 2017.

FORMULA

a(n) = b(n)^5*b(3*n)*b(5*n)/(b(2*n)^4*b(4*n)) where b(n) = 1!*2!*...*(n-1)! is a superfactorial A000178(n-1).

a(n) = c(n)*b(3*n)^2*b(6*n)/((7*n^2)!*b(2*n)^2*b(4*n)^2) where b(n) = 1!*2!*...*(n-1)! is a superfactorial A000178(n-1) and c(n) = A291871.

EXAMPLE

For n=1 we have that a(1)=8 since the Schubert polynomial of 351624 equals the following sum of eight monomials: x0^3*x1^3*x2 + x0^3*x1^2*x2^2 + x0^2*x1^3*x2^2 + x0^3*x1^3*x3 + x0^3*x1^2*x2*x3 + x0^2*x1^3*x2*x3 + x0^3*x1^2*x3^2 + x0^2*x1^3*x3^2.

PROG

(Sage) def b(n): return mul([factorial(i) for i in range(1, n)])

def a(n): return b(n)^5*b(3*n)^2*b(5*n)/(b(2*n)^4*b(4*n)^2)

[a(n) for n in range(10)]

(PARI) b(n) = prod(k=1, n-1, k!);

a(n) = b(n)^5*b(3*n)^2*b(5*n)/(b(2*n)^4*b(4*n)^2); \\ Michel Marcus, Sep 07 2017

CROSSREFS

Cf. A000178, A008793, A291871.

Sequence in context: A114133 A221233 A173190 * A281450 A278854 A115442

Adjacent sequences:  A291876 A291877 A291878 * A291880 A291881 A291882

KEYWORD

nonn

AUTHOR

Alejandro H. Morales, Sep 05 2017

STATUS

approved

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Last modified September 22 16:55 EDT 2019. Contains 327311 sequences. (Running on oeis4.)