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 A181106 #16 Nov 16 2019 13:22:14
%S A181106 -1,3,7,15,23,35,47,63,79,99,119,143,167,195,223,255,287,323,359,399,
%T A181106 439,483,527,575,623,675,727,783,839,899,959,1023,1087,1155,1223,1295,
%U A181106 1367,1443,1519,1599,1679,1763,1847,1935,2023,2115,2207,2303,2399,2499
%N A181106 Largest odd number strictly less than a square.
%C A181106 The terms are the negatives of A141354 and therefore have the same generating function except the sign.
%H A181106 Colin Barker, <a href="/A181106/b181106.txt">Table of n, a(n) for n = 1..1000</a>
%H A181106 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (2,0,-2,1).
%F A181106 a(n) = n^2 - 2^(n mod 2) = -A141354(n-1).
%F A181106 From _Colin Barker_, Jun 27 2015: (Start)
%F A181106 a(n) = n^2 - 1 for n even; a(n) = n^2 - 2 for n odd.
%F A181106 a(n) = 2*a(n-1) - 2*a(n-3) + a(n-4).
%F A181106 G.f.: x*(x^3-x^2-5*x+1) / ((x-1)^3*(x+1)).
%F A181106 (End)
%t A181106 Table[n^2-2^Mod[n,2],{n,50}] (* _Ray Chandler_, Dec 05 2011*)
%t A181106 LinearRecurrence[{2,0,-2,1},{-1,3,7,15},50] (* _Harvey P. Dale_, Nov 16 2019 *)
%o A181106 (PARI) Vec(x*(x^3-x^2-5*x+1)/((x-1)^3*(x+1)) + O(x^100)) \\ _Colin Barker_, Jun 27 2015
%Y A181106 Equals minus A141354.
%Y A181106 Cf. A120413 (Largest even number strictly less than a square).
%K A181106 easy,sign
%O A181106 1,2
%A A181106 Jerzy Kocik (jkocik(AT)siu.edu), Oct 03 2010
%E A181106 Edited by _Ray Chandler_, Dec 05 2011