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 A194073 #22 Jun 26 2025 11:49:20
%S A194073 1,4,7,13,19,28,37,49,61,76,91,109,127,148,169,193,217,244,271,301,
%T A194073 331,364,397,433,469,508,547,589,631,676,721,769,817,868,919,973,1027,
%U A194073 1084,1141,1201,1261,1324,1387,1453,1519,1588,1657,1729,1801
%N A194073 a(n) = 1 + floor((3/4)*n^2).
%H A194073 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (2,0,-2,1).
%F A194073 a(n) = 1 + floor((3/4)*n^2).
%F A194073 G.f.: x*(1+2*x-x^2+x^3) / ( (1+x)*(1-x)^3 ). - _R. J. Mathar_, Aug 25 2011
%F A194073 a(n) = 1 + 3*A002620(n). - _R. J. Mathar_, Aug 25 2011
%F A194073 a(n) = 2*a(n-1) - 2*a(n-3) + a(n-4). - _Wesley Ivan Hurt_, Jun 26 2025
%t A194073 c[k_]:=1+Floor[(3/4)k^2];
%t A194073 Table[c[k],{k,1,90}]
%o A194073 (PARI) a(n)=3*n^2\4+1 \\ _Charles R Greathouse IV_, Oct 16 2015
%Y A194073 Cf. A002620, A194074 (natural fractal sequence of A194073), A194075 (natural interspersion of A194074).
%K A194073 nonn,easy
%O A194073 1,2
%A A194073 _Clark Kimberling_, Aug 14 2011