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1, 3, 19, 271, 7085, 251429, 10997806, 564316854, 33175912910, 2196968168590, 161790768056642, 13114202824936638, 1160158996141467678, 111226473580172327222, 11486922450679555836573
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OFFSET
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1,2
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COMMENTS
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Partial sums of number of inequivalent ways of choosing n squares from an n X n board, considering rotations and reflections to be the same.The subsequence of primes in this partial sum (unexpectedly dense at first) begins: 3, 19, 271, 251429, no more through a(20) yet 4 of the first 5 values after a(1).
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LINKS
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FORMULA
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a(n) = SUM[i=1..n] A019318(i) = SUM[i=1..n] {number of inequivalent ways of choosing i squares from an i X i board, considering rotations and reflections to be the same}.
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EXAMPLE
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a(6) = 1 + 2 + 16 + 252 + 6814 + 244344 = 251429 is prime.
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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