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A375352
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Numbers k such that 14*k + 2 is a square.
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0
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1, 7, 23, 41, 73, 103, 151, 193, 257, 311, 391, 457, 553, 631, 743, 833, 961, 1063, 1207, 1321, 1481, 1607, 1783, 1921, 2113, 2263, 2471, 2633, 2857, 3031, 3271, 3457, 3713, 3911, 4183, 4393, 4681, 4903, 5207, 5441, 5761, 6007, 6343, 6601, 6953, 7223, 7591, 7873
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OFFSET
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1,2
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COMMENTS
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a(11) = 391 is first composite number in this sequence.
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LINKS
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FORMULA
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E.g.f.: ((2 + x + 7*x^2)*cosh(x) + (1 - x + 7*x^2)*sinh(x) - 2)/2. - Stefano Spezia, Aug 13 2024
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MATHEMATICA
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((Table[14*n + {4, 10}, {n, 0, 23}] // Flatten)^2 - 2)/14 (* Amiram Eldar, Aug 13 2024 *)
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PROG
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(Magma) [k: k in [0..8000] | IsSquare(14*k + 2)];
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CROSSREFS
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KEYWORD
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nonn,easy,new
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AUTHOR
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STATUS
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approved
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