cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A338875 Array T(n, m) read by ascending antidiagonals: numerators of shifted Fubini numbers F(n, m) where m >= 0.

Original entry on oeis.org

1, 1, 1, 3, 1, 1, 13, 5, 1, 1, 75, 2, 5, 1, 1, 541, 191, 29, 29, 1, 1, 4683, 76, 263, 149, 7, 1, 1, 47293, 5081, 4157, 24967, 2687, 727, 1, 1, 545835, 674, 93881, 115567, 44027, 66247, 631, 1, 1, 7087261, 386237, 21209, 377909, 31627, 37728769, 354061, 4481, 1, 1
Offset: 0

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Author

Stefano Spezia, Dec 25 2020

Keywords

Examples

			Array T(n, m):
n\m|   0       1       2       3 ...
---+--------------------------------
0  |   1       1       1       1 ...
1  |   1       1       1       1 ...
2  |   3       5       5      29 ...
3  |  13       2      29     149 ...
...
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 ...
  ...
		

Crossrefs

Cf. A000012 (n = 0 and n = 1), A000670 (m = 0), A226513 (high-order Fubini numbers), A232472, A232473, A232474, A257565, A338873, A338874.
Cf. A338876 (denominators).

Programs

  • 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[Numerator[F[n-m,m]],{n,0,9},{m,0,n}]//Flatten
  • 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) = numerator(n!*matdet(tm(n, m))); \\ Michel Marcus, Dec 31 2020

Formula

T(n, m) = numerator(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).