data/problems/275.yml
---
:id: 275
:name: Balanced Sculptures
:url: https://projecteuler.net/problem=275
:content: "Let us define a _balanced sculpture_ of order <var>n</var> as follows:\n\n-
A <dfn title=\"An arrangement of identical squares connected through shared edges;
holes are allowed.\">polyomino</dfn> made up of <var>n</var>+1 tiles known as the
_blocks_ (<var>n</var> tiles) \n and the _plinth_ (remaining tile);\n- the plinth
has its centre at position (<var>x</var> = 0, <var>y</var> = 0);\n- the blocks have
<var>y</var>-coordinates greater than zero (so the plinth is the unique lowest tile);\n-
the centre of mass of all the blocks, combined, has <var>x</var>-coordinate equal
to zero.\n\nWhen counting the sculptures, any arrangements which are simply reflections
about the <var>y</var>-axis, are <u>not</u> counted as distinct. For example, the
18 balanced sculptures of order 6 are shown below; note that each pair of mirror
images (about the <var>y</var>-axis) is counted as one sculpture:\n\n ![p275_sculptures2.gif]({{
images_dir }}/p275_sculptures2.gif)\n\nThere are 964 balanced sculptures of order
10 and 360505 of order 15. \nHow many balanced sculptures are there of order 18?\n\n"