A217154 - OEIS

A217154

Number of perfect squared rectangles of order n up to symmetries of the rectangle.

0, 0, 0, 0, 0, 0, 0, 0, 2, 14, 62, 235, 821, 2868, 10193, 36404, 130174, 466913, 1681999, 6083873

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OFFSET

1,9

COMMENTS

A squared rectangle (which may be a square) is a rectangle dissected into a finite number, two or more, of squares. If no two of these squares have the same size the squared rectangle is perfect. The order of a squared rectangle is the number of constituent squares.

A squared rectangle is simple if it does not contain a smaller squared rectangle, compound if it does, and trivially compound if a constituent square has the same side length as a side of the squared rectangle under consideration.

REFERENCES

See crossrefs for references and links.

LINKS

Table of n, a(n) for n=1..20.

Index entries for squared rectangles

Index entries for squared squares

FORMULA

a(n) = A002839(n) + A217153(n) + A217375(n).

a(n) >= 2*a(n-1) + A002839(n) + 2*A002839(n-1) + A217153(n) + 2*A217153(n-1), with equality for n<19.

EXAMPLE

a(10) = 14 comprises the A002839(10) = 6 simple perfect squared rectangles (SPSRs) of order 10 and the 8 trivially compound perfect squared rectangles which each comprises one of the two order 9 SPSRs and one other square.

CROSSREFS

Cf. A110148 (counts symmetries of any squared subrectangles as equivalent).

Cf. A181735, A217156.

Sequence in context: A095376 A153332 A331822 * A144657 A362157 A167555

Adjacent sequences: A217151 A217152 A217153 * A217155 A217156 A217157

KEYWORD

nonn,hard,more

AUTHOR

Geoffrey H. Morley, Sep 27 2012

EXTENSIONS

a(19) and a(20) corrected by Geoffrey H. Morley, Oct 12 2012

STATUS

approved

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