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A338876 Array T(n, m) read by ascending antidiagonals: denominators of shifted Fubini numbers F(n, m) where m >= 0. 3
1, 1, 1, 1, 2, 1, 1, 6, 6, 1, 1, 1, 36, 24, 1, 1, 30, 180, 1440, 120, 1, 1, 3, 1080, 11520, 2400, 720, 1, 1, 42, 9072, 2419200, 2016000, 1814400, 5040, 1, 1, 1, 90720, 11612160, 60480000, 435456000, 12700800, 40320, 1, 1, 90, 7776, 33177600, 69120000, 548674560000, 21337344000, 812851200, 362880, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,5

LINKS

Table of n, a(n) for n=0..54.

Takao Komatsu, Shifted Bernoulli numbers and shifted Fubini numbers, Linear and Nonlinear Analysis, Volume 6, Number 2, 2020, 245-263.

FORMULA

T(n, m) = denominator(F(n, m)).

F(n, m) = n!*det(M(n, m)) where M(n, m) is the n X n Toeplitz matrix whose first row consists in 1/(m + 1)!, 1, 0, ..., 0 and whose first column consists in 1/(m + 1)!, -1/(m + 2)!, ..., (-1)^(n-1)/(m + n)! (see Proposition 5.1 in Komatsu).

F(n, m) = n!*Sum_{k=0..n-1} F(k, m)/((n - k + m)!*k!) for n > 0 and m >= 0 with F(0, m) = 1 (see Lemma 5.2).

F(n, m) = [x^n] n!*x^m/(x^m - exp(x) + E_m(x)), where E_m(x) = Sum_{n=0..m} x^n/n! (see Theorem 5.3 in Komatsu).

F(n, m) = n!*Sum_{k=1..n} Sum_{i_1+...+i_k=n, i_1,...,i_k>=1} Product_{j=1..k} 1/(i_j + m)! for n > 0 and m >= 0 (see Theorem 5.4).

F(1, m) = 1/(m + 1)! (see Theorem 5.5 in Komatsu).

F(n, m) = n!*Sum_{t_1+2*t_2+...+n*t_n=n} (t_1,...,t_n)!*(-1)^(n-t_1-...-t_n)*Product_{j=1..n} (1/(m + j)!)^t_j for n >= m >= 1 (see Theorem 5.7 in Komatsu).

(-1)^(n-1)/(n + m)! = det(M(n, m)) where M(n, m) is the n X n Toeplitz matrix whose first row consists in F(1, m), 1, 0, ..., 0 and whose first column consists in F(1, m), F(2, m)/2!, ..., F(n, m)/n! for n > 0 (see Theorem 5.8 in Komatsu).

Sum_{k=0..n} binomial(n, k)*F(k, m)*F(n-k, m) = - n!/(m^2*m!)*Sum_{l=0..n-1} ((m! + 1)/(m*m!))^(n-l-1)*(l*(m! + 1) - m)/l!*F(l, m) - (n - m)/m*F(n, m) for m > 0 (see Theorem 5.11 in Komatsu).

EXAMPLE

Array T(n, m):

n\m|   0       1       2       3 ...

---+--------------------------------

0  |   1       1       1       1 ...

1  |   1       2       6      24 ...

2  |   1       6      36    1440 ...

3  |   1       1     180   11520 ...

...

Related table of shifted Fubini numbers F(n, m):

   1   1      1         1 ...

   1 1/2    1/6      1/24 ...

   3 5/6   5/36   29/1440 ...

  13   2 29/180 149/11520 ...

  ...

MATHEMATICA

F[n_, m_]:=n!Coefficient[Series[x^m/(x^m-Exp[x]+Sum[x^k/k!, {k, 0, m}]), {x, 0, n}], x, n]; Table[Denominator[F[n-m, m]], {n, 0, 9}, {m, 0, n}]//Flatten

PROG

(PARI) tm(n, m) = {my(m = matrix(n, n, i, j, if (i==1, if (j==1, 1/(m + 1)!, if (j==2, 1)), if (j==1, (-1)^(i+1)/(m + i)!)))); for (i=2, n, for (j=2, n, m[i, j] = m[i-1, j-1]; ); ); m; }

T(n, m) = denominator(n!*matdet(tm(n, m))); \\ Michel Marcus, Dec 31 2020

CROSSREFS

Cf. A000012 (n = 0 or m = 0), A000142, A000670, A226513 (high-order Fubini numbers), A232472, A232473, A232474, A257565, A338873, A338874.

Cf. A338875 (numerators).

Sequence in context: A140956 A166919 A338874 * A260238 A283795 A168641

Adjacent sequences:  A338873 A338874 A338875 * A338877 A338878 A338879

KEYWORD

nonn,frac,tabl

AUTHOR

Stefano Spezia, Dec 25 2020

STATUS

approved

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Last modified June 14 07:10 EDT 2021. Contains 345018 sequences. (Running on oeis4.)