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A253599
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Centered square numbers (A001844) which are also centered heptagonal numbers (A069099).
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3
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1, 841, 43513, 54236113, 2807177521, 3498988573081, 181102250526121, 225733748749491361, 11683630587634972513, 14562987063325697070313, 753757743549580366157401, 939516547177660272044661361, 48627927055673997154643575441, 60611970510056587727363585953081
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OFFSET
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1,2
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LINKS
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Colin Barker, Table of n, a(n) for n = 1..416
Index entries for linear recurrences with constant coefficients, signature (1,64514,-64514,-1,1).
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FORMULA
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a(n) = a(n-1)+64514*a(n-2)-64514*a(n-3)-a(n-4)+a(n-5).
G.f.: -x*(x^4+840*x^3-21842*x^2+840*x+1) / ((x-1)*(x^2-254*x+1)*(x^2+254*x+1)).
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EXAMPLE
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841 is in the sequence because it is the 21st centered square number and the 16th centered heptagonal number.
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PROG
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(PARI) Vec(-x*(x^4+840*x^3-21842*x^2+840*x+1)/((x-1)*(x^2-254*x+1)*(x^2+254*x+1)) + O(x^100))
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CROSSREFS
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Cf. A001844, A069099, A253459, A253460.
Sequence in context: A210470 A108324 A133496 * A121499 A253514 A342841
Adjacent sequences: A253596 A253597 A253598 * A253600 A253601 A253602
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KEYWORD
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nonn,easy
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AUTHOR
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Colin Barker, Jan 05 2015
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STATUS
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approved
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