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.

Showing 1-2 of 2 results.

A062155 Number of n-row matrices over {0,1,2} with all row and column sums equal to 1 or 2.

Original entry on oeis.org

1, 3, 38, 1107, 58938, 5002470, 620355870, 105848185590, 23785613520480, 6809213491925040, 2419333087316808600, 1044664066287091958400, 538796052743780959419600, 327150260492074733413299600, 230994366606893955257329737600, 187668642106165851767306588418000
Offset: 0

Views

Author

Vladeta Jovovic, Jun 06 2001

Keywords

Examples

			There are 38 2-row matrices over {0,1,2} with all row and column sums equal to 1 or 2: 1 of type 2 X 1, 13 of type 2 X 2, 18 of type 2 X 3 and 6 of type 2 X 4, cf. A062154.
		

References

  • I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 1983,(Problem 3.4.15).

Crossrefs

Row sums of A062154.
Cf. A062156.

Programs

  • PARI
    seq(n)={[subst(serlaplace(p),y,1) | p <- Vec(serlaplace(1/sqrt(1-x*y + O(x*x^n))*exp(x*y/2+1/(1-x*y)*(x*y+x^2*y/2+x*y^2/2) + O(x*x^n))))]} \\ Andrew Howroyd, Feb 03 2021

Extensions

Terms a(14) and beyond from Andrew Howroyd, Feb 03 2021

A062156 Number of n X n matrices over {0,1,2} with all row and column sums equal to 1 or 2.

Original entry on oeis.org

1, 2, 13, 189, 4842, 190080, 10520010, 777018690, 73646397720, 8696221929360, 1249994376199800, 214673857998276600, 43377963701592920400, 10180798532673708139200, 2745082427076790292091600, 842339587833332705318202000, 291745985923439508815578224000
Offset: 0

Views

Author

Vladeta Jovovic, Jun 06 2001

Keywords

Examples

			There are 13 2 X 2 matrices over {0,1,2} with all row and column sums equal to 1 or 2, cf. A062154.
		

References

  • I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 1983,(Problem 3.4.15).

Crossrefs

Main diagonal of A062154.
Cf. A062155.

Extensions

Terms a(15) and beyond from Andrew Howroyd, Feb 03 2021
Showing 1-2 of 2 results.