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 A291412 #7 Sep 27 2017 09:25:05 %S A291412 1,4,10,24,62,156,391,987,2484,6252,15744,39636,99788,251237,632525, %T A291412 1592480,4009326,10094104,25413498,63982496,161086011,405559431, %U A291412 1021059816,2570679048,6472089792,16294506424,41023988824,103284359545,260034658537,654678248796 %N A291412 p-INVERT of (1,1,0,0,0,0,...), where p(S) = 1 - S - 2 S^2 + S^3. %C A291412 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 A291412 See A291382 for a guide to related sequences. %H A291412 Clark Kimberling, <a href="/A291412/b291412.txt">Table of n, a(n) for n = 0..1000</a> %H A291412 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (1, 3, 3, -1, -3, -1) %F A291412 G.f.: -(((1 + x) (-1 - 2 x - x^2 + 2 x^3 + x^4))/(1 - x - 3 x^2 - 3 x^3 + x^4 + 3 x^5 + x^6)). %F A291412 a(n) = a(n-1) + 3*a(n-2) + 3*a(n-3) - a(n-4) - 3*a(n-5) - a(n-6) for n >= 7. %t A291412 z = 60; s = x + x^2; p = 1 - s - 2 s^2 + s^3; %t A291412 Drop[CoefficientList[Series[s, {x, 0, z}], x], 1] (* A019590 *) %t A291412 Drop[CoefficientList[Series[1/p, {x, 0, z}], x], 1] (* A291412 *) %o A291412 (GAP) %o A291412 a:=[1,4,10,24,62,156];; for n in [7..10^2] do a[n]:=a[n-1]+3*a[n-2]+3*a[n-3]-a[n-4]-3*a[n-5]-a[n-6]; od; a; # _Muniru A Asiru_, Sep 12 2017 %Y A291412 Cf. A019590, A291382. %K A291412 nonn,easy %O A291412 0,2 %A A291412 _Clark Kimberling_, Sep 07 2017