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 A291243 #10 Aug 29 2017 03:34:09 %S A291243 3,8,24,71,210,621,1836,5428,16047,47440,140247,414612,1225716, %T A291243 3623579,10712370,31668929,93622704,276776352,818232603,2418937120, %U A291243 7151092203,21140739568,62498266944,184763326671,546214936050,1614772594421,4773744472356,14112597876668 %N A291243 p-INVERT of (0,1,0,1,0,1,...), where p(S) = 1 - 3 S + S^2. %C A291243 Suppose s = (c(0), c(1), c(2), ...) is a sequence and p(S) is a polynomial. Let S(x) = c(0)*x + c(1)*x^2 + c(2)*x^3 + ... and T(x) = (-p(0) + 1/p(S(x)))/x. The p-INVERT of s is the sequence t(s) of coefficients in the Maclaurin series for T(x). Taking p(S) = 1 - S gives the "INVERT" transform of s, so that p-INVERT is a generalization of the "INVERT" transform (e.g., A033453). %C A291243 See A291219 for a guide to related sequences. %H A291243 Clark Kimberling, <a href="/A291243/b291243.txt">Table of n, a(n) for n = 0..1000</a> %H A291243 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (3,1,-3,-1) %F A291243 G.f.: (3 - x - 3*x^2)/(1 - 3*x - x^2 + 3*x^3 + x^4). %F A291243 a(n) = 3*a(n-1) + a(n-2) - 3*a(n-3) - a(n-4) for n >= 5. %t A291243 z = 60; s = x/(1 - x^2); p = 1 - 3 s - s^2; %t A291243 Drop[CoefficientList[Series[s, {x, 0, z}], x], 1] (* A000035 *) %t A291243 Drop[CoefficientList[Series[1/p, {x, 0, z}], x], 1] (* A291243 *) %Y A291243 Cf. A000035, A291219. %K A291243 nonn,easy %O A291243 0,1 %A A291243 _Clark Kimberling_, Aug 28 2017