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A259160
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Positive squares (A000290) that are octagonal numbers (A000567) divided by 2.
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3
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4, 39204, 376437604, 3614553835204, 34706945549192004, 333256087548787788004, 3199924917936514791223204, 30725678728770327476537417604, 295027963953727766493197492611204, 2832858479158015285097354847515364004, 27201106821847298813777034752645032556004
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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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FORMULA
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G.f.: -4*x*(x^2+198*x+1) / ((x-1)*(x^2-9602*x+1)).
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EXAMPLE
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4 is in the sequence because 4 is the 2nd square, and 2*4 is the 2nd octagonal number.
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MATHEMATICA
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LinearRecurrence[{9603, -9603, 1}, {4, 39204, 376437604}, 20] (* Vincenzo Librandi, Jun 20 2015 *)
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PROG
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(PARI) Vec(-4*x*(x^2+198*x+1)/((x-1)*(x^2-9602*x+1)) + O(x^20))
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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