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 A111570 #16 Feb 07 2025 00:34:47 %S A111570 2,5,4,7,14,23,34,55,92,149,238,385,626,1013,1636,2647,4286,6935, %T A111570 11218,18151,29372,47525,76894,124417,201314,325733,527044,852775, %U A111570 1379822,2232599,3612418,5845015,9457436,15302453,24759886 %N A111570 a(n) = a(n-1) + a(n-3) + a(n-4), n >= 4, with initial terms 2,5,4,7. %C A111570 See comment and FAMP code for A111569. %C A111570 Floretion Algebra Multiplication Program, FAMP Code: 1vesseq[B+H] with B = - .25'i + .25'j - .25i' + .25j' + k' - .5'kk' - .25'ik' - .25'jk' - .25'ki' - .25'kj' - .5e and H = + .75'ii' + .75'jj' + .75'kk' + .75e %H A111570 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (1, 0, 1, 1). %F A111570 G.f.: (-2-3*x+x^2-x^3)/((1+x^2)*(x^2+x-1)). %Y A111570 Cf. A001638, A111569, A111571, A111572, A111573, A007598, A000045. %K A111570 easy,nonn %O A111570 0,1 %A A111570 _Creighton Dement_, Aug 10 2005 %E A111570 Name clarified by _Robert C. Lyons_, Feb 06 2025