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 A131040 #15 Dec 07 2019 12:18:25 %S A131040 1,-5,-8,7,31,10,-83,-113,136,475,67,-1358,-1559,2515,7192,-353, %T A131040 -21929,-20870,44917,107527,-27224,-349805,-268133,781282,1585681, %U A131040 -758165,-5515208,-3240713,13304911,23027050,-16887683,-85968833,-35305784 %N A131040 a(n) = (1/2+1/2*i*sqrt(11))^n + (1/2-1/2*i*sqrt(11))^n, where i=sqrt(-1). %C A131040 Generating floretion is 1.5i' + .5j' + .5k' + .5e whereas in A131039 it is 'i + .5i' + .5j' + .5k' + .5e %C A131040 Essentially the Lucas sequence V(1,3). - _Peter Bala_, Jun 23 2015 %H A131040 Wikipedia, <a href="http://en.wikipedia.org/wiki/Lucas_sequence">Lucas sequence</a> %F A131040 a(n) = a(n-1) - 3*a(n-2); G.f. (1 - 6*x)/(1 - x + 3*x^2). %F A131040 a(n) = [x^n] ( (1 + x + sqrt(1 + 2*x - 11*x^2))/2 )^n. - _Peter Bala_, Jun 23 2015 %p A131040 Floretion Algebra Multiplication Program, FAMP Code: 2tesseq[ 1.5i' + .5j' + .5k' + .5e] %o A131040 (Sage) [lucas_number2(n,1,3) for n in range(1, 34)] # _Zerinvary Lajos_, May 14 2009 %Y A131040 Cf. A131039, A131041, A131042, A002316, A002531. %K A131040 easy,sign %O A131040 0,2 %A A131040 _Creighton Dement_, Jun 11 2007