A393938 Triangle read by rows: T(n,k) is the number of free polycubes with n cells, where the maximum number of collinear cell centers is k; 1 <= k <= n.

1, 0, 1, 0, 1, 1, 0, 4, 2, 1, 0, 5, 15, 2, 1, 0, 18, 69, 21, 3, 1, 0, 33, 401, 138, 31, 3, 1, 0, 67, 2335, 1133, 231, 40, 4, 1, 0, 82, 13976, 8904, 2055, 338, 53, 4, 1, 0, 129, 84367, 71880, 17791, 3343, 502, 65, 5, 1, 0, 190, 511595, 573917, 156444, 31348, 5272, 684, 81, 5, 1

Offset

1,8

Links

Table of n, a(n) for n=1..66.

Example

Triangle begins:
  n\k| 1   2      3      4      5     6    7   8  9 10 11
  ---+---------------------------------------------------
   1 | 1
   2 | 0   1
   3 | 0   1      1
   4 | 0   4      2      1
   5 | 0   5     15      2      1
   6 | 0  18     69     21      3     1
   7 | 0  33    401    138     31     3    1
   8 | 0  67   2335   1133    231    40    4   1
   9 | 0  82  13976   8904   2055   338   53   4  1
  10 | 0 129  84367  71880  17791  3343  502  65  5  1
  11 | 0 190 511595 573917 156444 31348 5272 684 81  5  1

Crossrefs

Cf. A038119 (row sums), A377942 (polyominoes), A393939.

Sequence in context: A325146 A385686 A195152 * A085668 A256702 A266921

Adjacent sequences: A393935 A393936 A393937 * A393939 A393940 A393941

Keyword

nonn,tabl

Author

Pontus von Brömssen, Mar 04 2026

Status

approved