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A245585
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Numbers that cannot be written as sum of two quarter-squares, cf. A002620.
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3
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19, 23, 33, 35, 47, 59, 63, 71, 75, 77, 95, 103, 107, 118, 124, 129, 131, 143, 147, 155, 161, 167, 179, 187, 195, 201, 203, 206, 209, 215, 217, 223, 236, 239, 243, 247, 248, 251, 271, 275, 280, 283, 285, 287, 294, 299, 311, 316, 323, 327, 329, 332, 334, 339
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refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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COMMENTS
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LINKS
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MATHEMATICA
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qsQ[n_] := qsQ[n] = With[{s = Sqrt[n]}, Which[IntegerQ[s], True, n == Floor[s] (Floor[s] + 1), True, True, False]];
A245575[n_] := Count[Range[0, n], k_ /; qsQ[k] && qsQ[n - k]];
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PROG
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(Haskell)
a245585 n = a245585_list !! (n-1)
a245585_list = filter ((== 0) . a245575) [0..]
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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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