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.

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A318537 Irregular triangle read by rows: T(n,m) is the number of n X m (0,1)-matrices with pairwise distinct nonzero columns and pairwise distinct nonzero rows, n >= 0, m = 0..2^n-1.

Original entry on oeis.org

1, 0, 1, 0, 0, 6, 6, 0, 0, 6, 174, 840, 2520, 5040, 5040, 0, 0, 0, 840, 24360, 335160, 3553200, 32382000, 259459200, 1816214400, 10897286400, 54486432000, 217945728000, 653837184000, 1307674368000, 1307674368000, 0, 0, 0, 2520, 335160, 15198120, 476496720, 12767000400, 314181504000, 7288444800000
Offset: 0

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Author

Max Alekseyev, Aug 28 2018

Keywords

Comments

T(n,m) is divisible by both n! and m!, but not necessarily by n!*m!.
By symmetry T(n,m) = T(m,n).
T(n,2^n-1) = T(n,2^n-2) = (2^n-1)! = A028366(n).

Examples

			Triangle begins:
n=0: 1;
n=1: 0, 1;
n=2: 0, 0, 6, 6;
n=3: 0, 0, 6, 174, 840, 2520, 5040, 5040;
...
		

Crossrefs

Cf. A318538 (main diagonal), A059202.

Programs

  • PARI
    { A318537(n,m) = m! * sum(i=0,n, stirling(n+1,i+1)*binomial(2^i - 1,m)); }

Formula

T(n,m) = m! * Sum_{i=0..n} Stirling1(n+1,i+1) * binomial(2^i-1,m) = n! * Sum_{j=0..m} Stirling1(m+1,j+1) * binomial(2^j-1,n).
T(n,m) = A059202(n,m) * m!.
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