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T(n, 2n-9), T given by A027926.
2

%I #20 Sep 08 2022 08:44:49

%S 1,3,8,21,55,143,364,894,2098,4685,9955,20175,39130,72905,130965,

%T 227612,383911,630191,1009242,1580345,2424289,3649547,5399802,7863034,

%U 11282400,15969161,22317933,30824563,42106956,56929205

%N T(n, 2n-9), T given by A027926.

%H G. C. Greubel, <a href="/A027932/b027932.txt">Table of n, a(n) for n = 5..1000</a>

%H <a href="/index/Rec#order_10">Index entries for linear recurrences with constant coefficients</a>, signature (10,-45,120,-210,252,-210,120,-45,10,-1).

%F a(n) = Sum_{k=0..4} binomial(n-k, 9-2*k). - _Len Smiley_, Oct 20 2001

%F a(n) = C(n,n-1) + C(n+1,n-2) + C(n+2,n-3) + C(n+3,n-4) + C(n+4,n-5), n>=1 . - _Zerinvary Lajos_, May 29 2007

%F G.f.: x^5*(1 -7*x +23*x^2 -44*x^3 +55*x^4 -44*x^5 +23*x^6 -7*x^7 +x^8) / (1-x)^10 . - _R. J. Mathar_, Oct 31 2015

%p A027932 := proc(n)

%p 1/362880 *(n-4) *(n^8 -32*n^7 +490*n^6 -4592*n^5 +30289*n^4 -147728*n^3 +543780*n^2 -1359648*n +1905120)

%p end proc:

%p seq(A027932(n),n=5..30) ; # _R. J. Mathar_, Jun 29 2012

%t Sum[Binomial[Range[5, 40] -k, 9-2*k], {k,0,4}] (* _G. C. Greubel_, Sep 27 2019 *)

%o (PARI) vector(40, n, sum(k=0,4, binomial(n+4-k, 9-2*k)) ) \\ _G. C. Greubel_, Sep 27 2019

%o (Magma) [&+[Binomial(n-k, 9-2*k): k in [0..4]] : n in [5..40]]; // _G. C. Greubel_, Sep 27 2019

%o (Sage) [sum(binomial(n-k, 9-2*k) for k in (0..4)) for n in (5..40)] # _G. C. Greubel_, Sep 27 2019

%o (GAP) List([5..40], n-> Sum([0..4], k-> Binomial(n-k, 9-2*k)) ); # _G. C. Greubel_, Sep 27 2019

%Y Cf. A228074.

%K nonn,easy

%O 5,2

%A _Clark Kimberling_