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A274686
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Least number k such that k-th triangular number is the sum of two nonzero squares in exactly n ways.
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1
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4, 40, 25, 145, 625, 169, 31249, 985, 2600, 2500, 87890625, 3649, 384199200, 15625, 33124, 6409
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OFFSET
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1,1
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COMMENTS
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A025426(A000217(18463134765625))=17, but I don't know if this is minimal). (End)
a(18) = 24649, a(20) = 40000, a(21) = 250000. 25*10^6, 25*10^8, 25*10^12 are not terms. Are there other terms of the form 25*10^(2k)? - Chai Wah Wu, Jul 23 2020
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LINKS
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EXAMPLE
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a(2) = 40 because 40*41 / 2 = 820 = 6^2 + 28^2 = 12^2 + 26^2.
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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