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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.

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A368032 Number of free linear midpoint-free polycubes of size n, identifying rotations and reflections.

Original entry on oeis.org

1, 1, 1, 2, 3, 7, 11, 20, 34, 65, 113, 197, 315, 488, 685, 1002, 1409, 2019, 2679, 3667, 4837, 6558, 8474, 11018, 13786, 17882, 22431, 28918, 36411, 46905, 59183, 76343, 96372, 123464, 153738, 193710, 237629, 294513, 357010, 436593
Offset: 1

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Author

Joerg Arndt, Dec 09 2023

Keywords

Comments

Linear polycubes have two end points with one neighbor, the remaining cubes all have two neighbors.
Midpoint-free means that no three cubes are in positions (x,y,z), (x+dx,y+dx,z+dz), and (x+2*dx,y+2*dx,z+2*dz).

Examples

			The polycubes for n <= 6 are:
n=1:
  0,0,0
n=2:
  0,0,0; 0,0,1
n=3:
  0,0,0; 0,0,1; 0,1,0
n=4:
  0,0,0; 0,0,1; 0,1,0; 1,0,1
  0,0,0; 0,0,1; 0,1,1; 0,1,2
n=5:
  0,0,0; 0,0,1; 0,1,0; 1,0,1; 1,0,2
  0,0,0; 0,0,1; 0,1,0; 1,0,1; 1,1,0
  0,0,0; 0,0,1; 0,1,1; 1,1,1; 1,1,2
n=6:
  0,0,0; 0,0,1; 0,1,0; 1,0,1; 1,0,2; 1,1,0
  0,0,0; 0,0,1; 0,1,0; 1,0,1; 1,0,2; 1,1,2
  0,0,0; 0,0,1; 0,1,0; 1,0,1; 1,1,1; 1,1,2
  0,0,0; 0,0,1; 0,1,1; 0,1,2; 1,1,2; 1,1,3
  0,0,0; 0,0,1; 0,1,1; 0,1,2; 1,1,2; 1,2,2
  0,0,0; 0,0,1; 0,1,1; 1,1,1; 1,1,2; 1,2,2
  0,0,0; 0,0,1; 0,1,1; 1,1,1; 1,2,1; 1,2,2
		

Crossrefs

Cf. A368031.
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