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 A131039 #17 Mar 14 2024 15:19:46
%S A131039 1,-3,-5,7,26,0,-97,-97,265,627,-362,-2702,-1351,8733,13775,-18817,
%T A131039 -70226,0,262087,262087,-716035,-1694157,978122,7300802,3650401,
%U A131039 -23596563,-37220045,50843527,189750626,0,-708158977,-708158977,1934726305,4577611587,-2642885282,-19726764302,-9863382151
%N A131039 Expansion of (1-x)*(2*x^2-4*x+1)/(1-2*x+5*x^2-4*x^3+x^4).
%C A131039 Unsigned bisection gives match to A002316 (Related to Bernoulli numbers). Note that all numbers in A002316 appear to be in A002531 (Numerators of continued fraction convergents to sqrt(3)) as well. a(12*n+5) = (0,0,0,0,...)
%C A131039 Floretion Algebra Multiplication Program, FAMP Code: 2tesseq['i + .5i' + .5j' + .5k' + .5e]
%H A131039 Robert Israel, <a href="/A131039/b131039.txt">Table of n, a(n) for n = 0..3492</a>
%H A131039 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (2,-5,4,-1).
%F A131039 a(0)=1, a(1)=-3, a(2)=-5, a(3)=7, a(n)=2*a(n-1)-5*a(n-2)+4*a(n-3)-a(n-4) [_Harvey P. Dale_, Aug 31 2011]
%p A131039 f:= gfun:-rectoproc({a(0)=1, a(1)=-3, a(2)=-5, a(3)=7, a(n)=2*a(n-1)-5*a(n-2)+4*a(n-3)-a(n-4)},a(n),remember):
%p A131039 map(f, [$0..100]); # _Robert Israel_, Dec 25 2016
%t A131039 CoefficientList[Series[(1-x)(2x^2-4x+1)/(1-2x+5x^2-4x^3+x^4),{x, 0, 50}], x] (* or *) LinearRecurrence[{2,-5,4,-1},{1,-3,-5,7},50] (* _Harvey P. Dale_, Aug 31 2011 *)
%Y A131039 Cf. A131040, A131041, A131042, A002316, A002531.
%K A131039 easy,sign
%O A131039 0,2
%A A131039 _Creighton Dement_, Jun 11 2007