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 A165987 #24 Mar 14 2024 09:03:52 %S A165987 1099258818702,8792791182238,29674231047422,70337212371066, %T A165987 137375369109982,237382335220982,376951744660878,562677231386482, %U A165987 801152429354606,1098970972522062,1462726494845662,1899012630282218,2414423012788542,3015551276321446,3708991054837742 %N A165987 a(n) is the trace of the matrix f(X + n*f(X))/f(X), where X is the 2 X 2 matrix [-13, 17; 31, 97] and f(x) = x^3 - 5*x + 67. %C A165987 Old name was: As mentioned in the short description (cf. A165806 & A165808) polynomials have the property: f(x + k*f(x)) is congruent to 0 mod(f(x)). This is true even if the variable is a square matrix. For this sequence let X be a 2x2 matrix (X belongs to Z): col1:-13, 31;col2: 17, 97. Let the polynomial be X^3 -5X + 67. The present sequence is a sequence of traces of the matrices resulting from the division of f(X + k*f(X))/f(X). Here k belongs to N. %H A165987 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (4,-6,4,-1). %F A165987 G.f.: 2*(549309615337*x^3+2197877953721*x^2+549629409347*x+1)/(x-1)^4. - _Alois P. Heinz_, Mar 13 2024 %p A165987 with(LinearAlgebra): %p A165987 f:= x-> x^3-5*x+67: %p A165987 a:= n-> (X-> Trace(f(X+n*f(X)).f(X)^(-1)))(<<-13|17>, <31|97>>): %p A165987 seq(a(n), n=1..15); # _Alois P. Heinz_, Mar 13 2024 %Y A165987 Cf. A165806, A165808. %K A165987 nonn,easy,less %O A165987 1,1 %A A165987 _A.K. Devaraj_, Oct 03 2009 %E A165987 a(5)-a(15) added and edited by _Alois P. Heinz_, Mar 13 2024