[seqfan] Re: How many ways to dissect a square into 4 congruent pieces

Don Reble djr at nk.ca
Wed May 13 15:39:13 CEST 2015

> ...A003213. Sent to me by Tom Parkin

    a(2)=5, not 6, and so it would be good to clearly state why these
    two are the same:

0001 0001
0111 0111
2223 2333
2333 2223

    Thankfully, Tom's algorithm is far simpler than his 1970s language
    would suggest. One detail is missing: he doesn't state how not to
    count reflections of an earlier figure. (This problem can happen
    only when starting at the middle of the square's side, or at the
    middle of the rectangle's longer side.)

    Tom must have resolved it. Otherwise Table 1 would be wrong at
    N=3 {Square} 3,0: he got 5 (correct) instead of 9 (wrong).

    We still disagree, however. My values for N=4 {Square} are
    212,167,146,71. (Tom has same,same,same,87.)

    Could someone provide a third opinion?

Don Reble  djr at nk.ca

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