A024201 - OEIS

%I #26 Apr 03 2026 15:11:37

%S 0,2,5,9,14,19,26,34,43,53,64,75,88,102,117,133,150,167,186,206,227,

%T 249,272,295,320,346,373,401,430,459,490,522,555,589,624,659,696,734,

%U 773,813,854,895,938,982,1027,1073,1120,1167,1216,1266,1317,1369,1422,1475

%N [ (2nd elementary symmetric function of S(n))/(first elementary symmetric function of S(n)) ], where S(n) = {first n+1 odd positive integers}.

%H <a href="/index/Rec#order_08">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1,0,0,0,1,-2,1).

%F G.f.: x^2*(x^6-2*x^5-x^3-x^2-x-2) / ((x-1)^3*(x+1)*(x^2-x+1)*(x^2+x+1)). - _Colin Barker_, Aug 15 2014

%F a(n) = floor( A024196(n)/(1+n)^2). - _R. J. Mathar_, Sep 23 2016

%F a(n) = (n^2 + n - 2)/2 - floor(n/6), n>=1. - _Muslim Alaa_, Apr 01 2026

%t LinearRecurrence[{2, -1, 0, 0, 0, 1, -2, 1}, {0, 2, 5, 9, 14, 19, 26, 34}, 55] (* _Hugo Pfoertner_, Mar 30 2026 *)

%K nonn,easy

%O 1,2

%A _Clark Kimberling_