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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

%I

%S 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,

%T 2400,720,1,1,42,9072,2419200,2016000,1814400,5040,1,1,1,90720,

%U 11612160,60480000,435456000,12700800,40320,1,1,90,7776,33177600,69120000,548674560000,21337344000,812851200,362880,1

%N Array T(n, m) read by ascending antidiagonals: denominators of shifted Fubini numbers F(n, m) where m >= 0.

%H Takao Komatsu, <a href="https://www.researchgate.net/publication/344595540_SHIFTED_BERNOULLI_NUMBERS_AND_SHIFTED_FUBINI_NUMBERS">Shifted Bernoulli numbers and shifted Fubini numbers</a>, Linear and Nonlinear Analysis, Volume 6, Number 2, 2020, 245-263.

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

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

%F 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).

%F (-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).

%F 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).

%e Array T(n, m):

%e n\m| 0 1 2 3 ...

%e ---+--------------------------------

%e 0 | 1 1 1 1 ...

%e 1 | 1 2 6 24 ...

%e 2 | 1 6 36 1440 ...

%e 3 | 1 1 180 11520 ...

%e ...

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

%e 1 1 1 1 ...

%e 1 1/2 1/6 1/24 ...

%e 3 5/6 5/36 29/1440 ...

%e 13 2 29/180 149/11520 ...

%e ...

%t 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

%o (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; }

%o T(n, m) = denominator(n!*matdet(tm(n, m))); \\ _Michel Marcus_, Dec 31 2020

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

%Y Cf. A338875 (numerators).

%K nonn,frac,tabl

%O 0,5

%A _Stefano Spezia_, Dec 25 2020

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Last modified July 25 19:34 EDT 2021. Contains 346291 sequences. (Running on oeis4.)