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.

A180985 Array T(n,k) = number of n X k binary matrices with rows and columns in lexicographically nondecreasing order.

Original entry on oeis.org

2, 3, 3, 4, 7, 4, 5, 14, 14, 5, 6, 25, 45, 25, 6, 7, 41, 130, 130, 41, 7, 8, 63, 336, 650, 336, 63, 8, 9, 92, 785, 2942, 2942, 785, 92, 9, 10, 129, 1682, 11819, 24520, 11819, 1682, 129, 10, 11, 175, 3351, 42305, 183010, 183010, 42305, 3351, 175, 11, 12, 231, 6280, 136564
Offset: 1

Views

Author

R. H. Hardin, Sep 30 2010

Keywords

Comments

Differs from "number of inequivalent {0,1}-matrices of size n X k, modulo permutations of rows and columns", A241956, starting at T(2, 3) = 14 while A241956(2, 3) = 13. - M. F. Hasler, Apr 27 2022

Examples

			Table starts:
..2...3.....4.......5.........6...........7.............8................9
..3...7....14......25........41..........63............92..............129
..4..14....45.....130.......336.........785..........1682.............3351
..5..25...130.....650......2942.......11819.........42305...........136564
..6..41...336....2942.....24520......183010.......1202234..........6979061
..7..63...785...11819....183010.....2625117......33345183........371484319
..8..92..1682...42305...1202234....33345183.....836488618......18470742266
..9.129..3351..136564...6979061...371484319...18470742266.....818230288201
.10.175..6280..402910..36211867..3651371519..358194085968...31887670171373
.11.231.11176.1099694.170079565.32017940222.6148026957098.1096628939510047
.
All solutions for 3 X 3:
..0..0..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0
..0..0..0....0..0..0....0..0..1....0..0..1....0..0..1....0..1..1....0..0..0
..0..0..1....0..1..1....0..1..0....0..0..1....0..1..1....0..1..1....1..1..1
.
..0..0..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..1....0..0..1
..0..0..1....0..1..1....0..0..1....0..1..1....0..1..1....0..1..0....0..1..0
..1..1..0....1..0..0....1..1..1....1..0..1....1..1..1....0..1..0....0..1..1
.
..0..0..1....0..0..1....0..0..1....0..0..1....0..0..1....0..0..1....0..0..1
..0..0..1....0..0..1....0..0..1....0..1..1....0..1..0....0..1..0....0..1..0
..0..1..0....0..0..1....0..1..1....0..1..1....1..0..0....1..1..0....1..0..1
.
..0..0..1....0..0..1....0..0..1....0..0..1....0..0..1....0..0..1....0..0..1
..0..1..0....0..0..1....0..1..1....0..1..1....0..0..1....0..1..1....0..1..1
..1..1..1....1..1..0....1..0..0....1..1..0....1..1..1....1..0..1....1..1..1
.
..0..0..0....0..0..1....0..0..1....0..0..1....0..1..1....0..1..1....0..1..1
..1..1..1....1..1..0....1..1..0....1..1..1....0..1..1....0..1..1....0..1..1
..1..1..1....1..1..0....1..1..1....1..1..1....0..1..1....1..0..0....1..0..1
...
..0..1..1....0..1..1....0..1..1....0..1..1....0..1..1....0..1..1....0..1..1
..0..1..1....1..0..0....1..0..0....1..0..0....1..0..1....1..0..1....1..0..1
..1..1..1....1..0..0....1..0..1....1..1..1....1..1..0....1..0..1....1..1..1
.
..0..1..1....1..1..1
..1..1..1....1..1..1
..1..1..1....1..1..1
		

Crossrefs

Cf. A089006 (diagonal).
Cf. A004006 (row & column 2), A184138 (row & column 3).
Cf. A241956 (similar but different).

Programs

  • PARI
    A180985(h,w,cnt=0)={ local(A=matrix(h,w), z(r,c)=!while(r1 && z(r,c), c--); while(c>1, A[r,c--]=0); while(r>1, A[r--,]=A[r+1,]); next(3))); break); cnt} \\ M. F. Hasler, Apr 27 2022

Formula

T(n,k) = T(k,n). T(1,k) = k+1. T(2,k) = A004006(k+1). T(3,k) = A184138(k). - M. F. Hasler, Apr 27 2022