A090163 -id:A090163 - cp's OEIS frontend

A090033 Triangle T(j,k) read by rows, where T(j,k) is the number of single tile moves in the longest optimal solution of the j X k generalization of the sliding block 15-puzzle, starting with the empty square in a corner.

0, 1, 6, 2, 21, 31, 3, 36, 53, 80, 4, 55, 84

Offset: 1

Hugo Pfoertner, Nov 23 2003

T(k,j) = T(j,k).

T(2,2), T(2,3), T(4,2), T(4,3) from Karlemo and Östergård, T(3,3) from Reinefeld, T(4,4) from Bruengger et al.

			The triangle begins
  0
  1   6
  2  21  31
  3  36  53  80
  4  55  84  ...
.
a(6)=T(3,3)=31 because the A090163(3,3)=2 longest optimal solution paths of the 3 X 3 (9-) sliding block puzzle have length 31 (see A089473).

For references and links see A087725(n)=T(n,n).

Cf. A087725, A089473, A089484, A090034, A090035, A090036, A090166, A090163 corresponding number of different configurations with largest distance.

Cf. A151944 same as this sequence, but written as full array.

# alst(), moves(), swap() in A089473
def T(j, k):  # chr(45) is '-'
    start, shape = "".join(chr(45+i) for i in range(j*k)), (j, k)
    return len(alst(start, shape))-1
for j in range(1, 5):
    for k in range(1, j+1):
        print(T(j,k), end=", ") # Michael S. Branicky, Aug 02 2021

T(5,3) copied from A151944 by Hugo Pfoertner, Aug 02 2021

A090034 Number of configurations of the 3 X 2 variant of Sam Loyd's sliding block 15-puzzle that require a minimum of n moves to be reached, starting with the empty square in one of the corners.

Original entry on oeis.org

1, 2, 3, 5, 6, 7, 10, 12, 12, 16, 23, 25, 28, 39, 44, 40, 29, 21, 18, 12, 6, 1

Offset: 0

Hugo Pfoertner, Nov 23 2003

Data from Karlemo and Östergård. See corresponding link in A087725.

			Starting with
123
45-
the most distant configuration corresponding to a(21)=1 is
45-
123 (i.e., it takes longest just to swap the two rows).

See A087725.

Hugo Pfoertner, Solutions of small n*2 sliding block puzzles.
Takaken, n-Puzzle Page.
Takaken, No. 32 (5 puzzles).

Cf. A087725, A089473, A090033, A090035, A090036, A090163, A090167.

# alst(), moves(), swap() in A089473
print(alst("-12345", (3, 2))) # Michael S. Branicky, Dec 30 2020

cp's OEIS Frontend

A090033 Triangle T(j,k) read by rows, where T(j,k) is the number of single tile moves in the longest optimal solution of the j X k generalization of the sliding block 15-puzzle, starting with the empty square in a corner.

Views

Author

Keywords

Comments

Examples

References

Crossrefs

Programs

Python

Extensions