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A068250
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1/24 the number of colorings of a 3 X 3 octagonal array with n colors.
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2
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3, 280, 5265, 47040, 271250, 1170288, 4105710, 12334080, 32837805, 79365000, 177200023, 370319040, 731732820, 1377981920, 2488927500, 4334174208, 7307669895, 11972250360, 19116135885, 29823640000, 45562619718, 68291480400, 100588847450, 145809331200
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OFFSET
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4,1
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LINKS
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Index entries for linear recurrences with constant coefficients, signature (10,-45,120,-210,252,-210,120,-45,10,-1).
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FORMULA
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G.f.: (832*x^5+4805*x^4+6630*x^3+2600*x^2+250*x+3)*x^4 / (x-1)^10.
a(n) = (n^9 -20*n^8 +174*n^7 -859*n^6 +2627*n^5 -5082*n^4 +6048*n^3 -4023*n^2 +1134*n)/24. (End)
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MAPLE
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a:= n-> (n-2)*(n-1)*(n^2-5*n+7)*(n-3)^4*n/24:
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PROG
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(Magma) [n*(n-3)^4*(n^4-8*n^3+24*n^2-31*n+14)/24: n in [4..27]]; // Bruno Berselli, May 04 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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