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 A131588 #9 Mar 14 2024 14:01:59 %S A131588 1,1,3,7,11,31,43,127,171,511,683,2047,2731,8191,10923,32767,43691, %T A131588 131071,174763,524287,699051,2097151,2796203,8388607,11184811, %U A131588 33554431,44739243,134217727,178956971,536870911,715827883,2147483647,2863311531 %N A131588 Interlaces A007583 with A083420. %C A131588 Floretion Algebra Multiplication Program, FAMP Code: minseq[A*B] with A = + .25'i + .25i' + .25'ii' + .25'jj' + .25'kk' + .25'jk' + .25'kj' + .25e and B = + 'i + 'j - 2'k (apart from initial term and signs) %H A131588 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,5,0,-4). %F A131588 a(n) = 5*a(n-2) - 4*a(n-4); a(n) = (5*2^n+(-2)^n-8*(-1)^n-4)/12; g.f. (1+x-2*x^2+2*x^3)/((x-1)*(2*x+1)*(2*x-1)*(x+1)) %Y A131588 Cf. A007583, A083420, A001045. %K A131588 easy,nonn %O A131588 0,3 %A A131588 _Creighton Dement_, Aug 30 2007