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A014800
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Squares of even pentagonal pyramidal numbers.
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5
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0, 36, 324, 1600, 15876, 38416, 82944, 302500, 527076, 876096, 2160900, 3240000, 4734976, 9474084, 13032100, 17640000, 30980356, 40297104, 51840000, 83283876, 104162436, 129231424, 194602500, 236421376, 285474816, 409252900, 486202500
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OFFSET
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0,2
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LINKS
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Index entries for linear recurrences with constant coefficients, signature (1,0,6,-6,0,-15,15,0,20,-20,0,-15,15,0,6,-6,0,-1,1).
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FORMULA
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G.f.: -4*x*(x^16 +143*x^15 +481*x^14 +1394*x^13 +9661*x^12 +10814*x^11 +15996*x^10 +45222*x^9 +25248*x^8 +23414*x^7 +33610*x^6 +9218*x^5 +5203*x^4 +3515*x^3 +319*x^2 +72*x +9)/((x -1)^7*(x^2 +x +1)^6). [Colin Barker, Nov 16 2012]
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MATHEMATICA
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Select[CoefficientList[Series[(x(2x+1))/(x-1)^4, {x, 0, 50}], x], EvenQ]^2 (* Harvey P. Dale, Feb 27 2012 *)
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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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