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A155154
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Number of right triangles with nonnegative integer coordinates less than or equal to n and one corner at the origin.
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0
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0, 3, 14, 33, 62, 101, 148, 207, 276, 353, 448, 547, 662, 785, 920, 1067, 1230, 1397, 1586, 1773, 1986, 2205, 2436, 2671, 2940, 3207, 3494, 3787, 4096, 4399, 4764, 5095, 5458, 5825, 6208, 6603, 7050, 7453, 7880, 8331, 8826, 9277, 9800, 10279, 10808
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OFFSET
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0,2
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LINKS
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PROG
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(PARI) a(n)=3*n^2+sum(a=1, n, sum(b = 1, n, 2*min(b*gcd(a, b)\a, (n - a)*gcd(a, b)\b) ) ) \\ Yurii Ivanov, Jun 25 2021
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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Emlyn Corrin (emlyn(AT)corrin.name), Jan 21 2009
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STATUS
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approved
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