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A247614
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a(n) = Sum_{k=0..9} binomial(18,k)*binomial(n,k).
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1
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1, 19, 190, 1330, 7315, 33649, 134596, 480700, 1562275, 4686825, 13079352, 34084128, 83204745, 191006115, 414237570, 852920310, 1675575165, 3155247975, 5719519850, 10018268150, 17013571223, 28096825757, 45238870040, 71179679480, 109665022415
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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 (10,-45,120,-210,252,-210,120,-45,10,-1).
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FORMULA
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G.f.: (1 +9*x +45*x^2 +165*x^3 +495*x^4 +1287*x^5 +3003*x^6 + 6435*x^7 +12870*x^8 +24310*x^9) / (1-x)^10.
a(n) = 10*a(n-1) -45*a(n-2) +120*a(n-3) -210*a(n-4) +252*a(n-5) -210*a(n-6) +120*a(n-7) -45*a(n-8) +10*a(n-9) -a(n-10).
a(n) = (181440 + 462101904*n - 1283316876*n^2 + 1433031524*n^3 - 853620201*n^4 + 303063726*n^5 - 66245634*n^6+8905416*n^7 - 678249*n^8 + 24310*n^9) / 181440.
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MATHEMATICA
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Table[(181440 + 462101904 n - 1283316876 n^2 + 1433031524 n^3 - 853620201 n^4 + 303063726 n^5 - 66245634 n^6 + 8905416 n^7 - 678249 n^8 + 24310 n^9)/181440, {n, 0, 40}] (* or *) CoefficientList[Series[(1 + 9 x + 45 x^2 + 165 x^3 + 495 x^4 + 1287 x^5 + 3003 x^6 + 6435 x^7 + 12870 x^8 + 24310 x^9)/(1 - x)^10, {x, 0, 40}], x]
LinearRecurrence[{10, -45, 120, -210, 252, -210, 120, -45, 10, -1}, {1, 19, 190, 1330, 7315, 33649, 134596, 480700, 1562275, 4686825}, 30] (* Harvey P. Dale, Jul 19 2019 *)
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PROG
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(Magma) m:=9; [&+[Binomial(2*m, k)*Binomial(n, k): k in [0..m]]: n in [0..40]]; /* or */ [(181440+462101904*n-1283316876*n^2+1433031524*n^3 -853620201*n^4+303063726*n^5-66245634*n^6 +8905416*n^7-678249*n^8+24310*n^9)/181440: n in [0..40]];
(Sage) m=9; [sum((binomial(2*m, k)*binomial(n, k)) for k in (0..m)) for n in (0..40)] # Bruno Berselli, Sep 23 2014
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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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