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 A075464 a(n) is the minimal number of nontrivial switch flippings needed to solve the all-ones lights out problem on an n X n square. 5
 1, 4, 5, 4, 15, 28, 33, 40, 25, 44, 55, 72, 105, 56, 117, 104, 147, 188, 141, 224, 245, 276, 231, 270, 353, 356, 405, 416, 345, 376, 553, 428, 469, 520, 563, 600, 761, 772, 561, 696, 891, 940, 953, 772, 1069, 1188, 971, 1096, 1165, 1220, 1317, 1256, 1487, 1400 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For squares having multiple possible solutions (see A075462, A075463), there may be nontrivial solutions involving *more* than this number of flips. REFERENCES See A075462 for references. LINKS Max Alekseyev and Zhao Hui Du, Table of n, a(n) for n = 1..78 (terms 1..60 from Max Alekseyev) Eric Weisstein's World of Mathematics, Lights Out Puzzle Zhao Hui Du, C code for the problem Please compile it by latest gcc with option -O3 -msse4.2 CROSSREFS Cf. A075462, A075463. Sequence in context: A184833 A281385 A279270 * A247858 A247860 A196756 Adjacent sequences:  A075461 A075462 A075463 * A075465 A075466 A075467 KEYWORD nonn,nice AUTHOR Eric W. Weisstein, Sep 17 2002 EXTENSIONS a(26)-a(29) from Les Reid, Sep 09 2007 a(30)-a(38) from Max Alekseyev, Sep 17 2009 Extended by Max Alekseyev, Sep 20 2009 STATUS approved

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Last modified October 17 19:24 EDT 2019. Contains 328127 sequences. (Running on oeis4.)