A055831 - OEIS

%I #20 Sep 08 2022 08:45:01

%S 5,15,31,54,85,125,175,236,309,395,495,610,741,889,1055,1240,1445,

%T 1671,1919,2190,2485,2805,3151,3524,3925,4355,4815,5306,5829,6385,

%U 6975,7600,8261,8959,9695,10470,11285,12141,13039

%N T(n,n-4), where T is the array in A055830.

%H G. C. Greubel, <a href="/A055831/b055831.txt">Table of n, a(n) for n = 4..1000</a>

%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (4,-6,4,-1).

%F a(n)  = (n-3)*(n^2+6*n-10)/6, n>3.

%F G.f.: x^4*(5-5*x+x^2)/(1-x)^4. - _R. J. Mathar_, Mar 13 2016

%F E.g.f.: (-30 - 6*x + 3*x^2 + (30 - 24*x + 6*x^2 + x^3)*exp(x))/6. - _G. C. Greubel_, Jan 21 2020

%p seq( (n-3)*(n^2+6*n-10)/6, n=4..40); # _G. C. Greubel_, Jan 21 2020

%t Table[(n-3)*(n^2+6*n-10)/6, {n,4,40}] (* _G. C. Greubel_, Jan 21 2020 *)

%o (PARI) a(n) = (n-3)*(n^2+6*n-10)/6; \\ _G. C. Greubel_, Jan 21 2020

%o (Magma) [(n-3)*(n^2+6*n-10)/6: n in [4..40]]; // _G. C. Greubel_, Jan 21 2020

%o (Sage) [(n-3)*(n^2+6*n-10)/6 for n in (4..40)] # _G. C. Greubel_, Jan 21 2020

%o (GAP) List([4..40], n-> (n-3)*(n^2+6*n-10)/6); # _G. C. Greubel_, Jan 21 2020

%Y Cf. A055830.

%K nonn,easy

%O 4,1

%A _Clark Kimberling_, May 28 2000