A342946 -id:A342946 - cp's OEIS frontend

A342947 Squares visited by the black knight when a white knight and a black knight are moving on a diagonally numbered board, always to the lowest available unvisited square; white moves first.

1, 9, 4, 3, 13, 7, 5, 10, 26, 18, 11, 30, 37, 48, 22, 31, 38, 46, 58, 49, 41, 52, 27, 33, 40, 51, 60, 70, 57, 67, 81, 93, 106, 123, 79, 68, 82, 71, 61, 74, 64, 36, 65, 78, 118, 77, 88, 100, 85, 97, 110, 124, 139, 155, 172, 193, 138, 154, 212, 232, 256, 191, 213

Offset: 1

Andrew Smith, Mar 30 2021

Board is numbered as follows:
   1  2  4  7 11 16  .
   3  5  8 12 17  .
   6  9 13 18  .
  10 14 19  .
  15 20  .
  21  .
   .
Both knights start on square 1, white moves to the lowest unvisited square (8), black then moves to the lowest unvisited square (9) and so on...
This sequence is finite, on the black knight's 5503rd step, square 3828 is visited, after which there are no unvisited squares within one knight move.

Cf. A338288, A338289, A338290, A342946, A342948.

# see program in A342948
A342947_lst = A342948_lst[::2] # Michael S. Branicky, Mar 30 2021

A342948 Squares visited by either knight when a white knight and a black knight are moving on a diagonally numbered board, always to the lowest available unvisited square; white moves first.

Original entry on oeis.org

1, 8, 9, 6, 4, 2, 3, 12, 13, 16, 7, 24, 5, 19, 10, 15, 26, 34, 18, 14, 11, 21, 30, 43, 37, 20, 48, 25, 22, 17, 31, 39, 38, 29, 46, 23, 58, 32, 49, 42, 41, 35, 52, 45, 27, 53, 33, 28, 40, 54, 51, 63, 60, 73, 70, 84, 57, 50, 67, 59, 81, 47, 93, 56, 106, 69, 123

Offset: 1

Andrew Smith, Mar 30 2021

Board is numbered as follows:
   1  2  4  7 11 16  .
   3  5  8 12 17  .
   6  9 13 18  .
  10 14 19  .
  15 20  .
  21  .
   .
Both knights start on square 1, white moves to the lowest unvisited square (8), black then moves to the lowest unvisited square (9) and so on...
This sequence is finite, on the 583rd move or the white knight's 292nd step, square 406 is visited, after which black wins and the game is over.

Cf. A338288, A338289, A338290, A342946, A342947.

KM=[(2, 1), (1, 2), (-1, 2), (-2, 1), (-2, -1), (-1, -2), (1, -2), (2, -1)]
def idx(loc): i, j = loc; return (i+j-1)*(i+j-2)//2 + j
def next_move(loc, visited):
  i, j = loc; moves = [(i+io, j+jo) for io, jo in KM if i+io>0 and j+jo>0]
  available = [m for m in moves if m not in visited]
  return min(available, default=None, key=lambda x: idx(x))
def aseq():
  loc, s, turn, alst = [(1, 1), (1, 1)], {(1, 1)}, 0, [1]
  m = next_move(loc[turn], s)
  while m != None:
    loc[turn], s, turn, alst = m, s|{m}, 1 - turn, alst + [idx(m)]
    m = next_move(loc[turn], s)
  return alst
A342948_lst = aseq() # Michael S. Branicky, Mar 30 2021

cp's OEIS Frontend

A342947 Squares visited by the black knight when a white knight and a black knight are moving on a diagonally numbered board, always to the lowest available unvisited square; white moves first.

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