This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A011890 #19 Oct 07 2024 14:06:48 %S A011890 0,0,0,0,3,7,15,26,42,63,90,123,165,214,273,341,420,510,612,726,855, %T A011890 997,1155,1328,1518,1725,1950,2193,2457,2740,3045,3371,3720,4092,4488, %U A011890 4908,5355,5827,6327,6854,7410,7995,8610,9255,9933,10642,11385,12161,12972,13818,14700 %N A011890 a(n) = floor( n*(n-1)*(n-2)/8 ). %H A011890 G. C. Greubel, <a href="/A011890/b011890.txt">Table of n, a(n) for n = 0..1000</a> %H A011890 <a href="/index/Rec#order_11">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1,0,0,0,0,1,-3,3,-1). %F A011890 From _R. J. Mathar_, Apr 15 2010: (Start) %F A011890 a(n) = +3*a(n-1) -3*a(n-2) +a(n-3) +a(n-8) -3*a(n-9) +3*a(n-10) -a(n-11). %F A011890 G.f.: x^4*(3-2*x+3*x^2-x^3+2*x^4+x^6)/((1-x)^4*(1+x)*(1+x^2)*(1+x^4)). (End) %t A011890 Floor[6*Binomial[Range[0,50], 3]/8] (* _G. C. Greubel_, Oct 06 2024 *) %o A011890 (Magma) [Floor(6*Binomial(n,3)/8): n in [0..50]]; // _G. C. Greubel_, Oct 06 2024 %o A011890 (SageMath) [6*binomial(n,3)//8 for n in range(51)] # _G. C. Greubel_, Oct 06 2024 %Y A011890 Cf. A011886. %K A011890 nonn %O A011890 0,5 %A A011890 _N. J. A. Sloane_ %E A011890 a(41) onwards from _G. C. Greubel_, Oct 06 2024