OFFSET
0,2
COMMENTS
Product of all matrix elements of n X n matrix M(i,j) = i+j (i,j=1..n). - Alexander Adamchuk, Apr 12 2006
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..20
FORMULA
a(n) = (n+1)*(Product_{i=0..n} (n+i)!)/Product_{i=1..n+1} i!.
a(n) = A000178(2n)/A000178(n)^2, i.e., "central supercombinations" by analogy with A000984. - Henry Bottomley, May 14 2005
a(n) = Product_{j=1..n} Product_{i=1..n} (i + j). - Alexander Adamchuk, Apr 12 2006
Asymptotic: a(n) ~ (2*n+1)^(2*n^2 + 2*n + 5/12)*(n+1)^(-n^2 - 2*n - 5/6) * exp(-zeta'(-1) - (3/2)*n^2 + 3/4)/(sqrt(2*Pi)). - Peter Luschny, Nov 26 2012
a(n) = BarnesG(2*n+2) / BarnesG(n+2)^2. - Vaclav Kotesovec, Feb 28 2019
a(n) ~ A * 2^(2*n*(n+1) - 1/12) * n^(n^2 - 5/12) / (sqrt(Pi) * exp(3*n^2/2 + 1/12)), where A = A074962 is the Glaisher-Kinkelin constant. - Vaclav Kotesovec, Dec 04 2023
EXAMPLE
Determinant of M(2) is 1/(x^4 + 12*x^3 + 53*x^2 + 102*x + 72) hence a(2)=72.
MAPLE
seq(mul(mul(k+j, j=1..n), k=1..n), n=0..8); # Zerinvary Lajos, Jun 01 2007
MATHEMATICA
Table[Product[Product[(i+j), {i, 1, n}], {j, 1, n}], {n, 0, 10}] (* Alexander Adamchuk, Apr 12 2006 *)
Table[BarnesG[2*n+2] / BarnesG[n+2]^2, {n, 0, 10}] (* Vaclav Kotesovec, Feb 28 2019 *)
PROG
(PARI) a(n)=(n+1)*prod(i=0, n, (n+i)!)/prod(i=1, n+1, i!)
(PARI) a(n) = prod(i=1, n, prod(j=1, n, i+j)); \\ Michel Marcus, Feb 27 2019
(Python)
from math import prod, factorial
def A079478(n): return prod(i+j for i in range(1, n) for j in range(i+1, n+1))**2*factorial(n)<<n # Chai Wah Wu, Nov 26 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Jan 15 2003
STATUS
approved