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 A130214 #15 Jan 17 2024 09:06:51
%S A130214 0,60,7800,976500,122070000,15258787500,1907348625000,238418579062500,
%T A130214 29802322387500000,3725290298460937500,465661287307734375000,
%U A130214 58207660913467382812500,7275957614183425781250000,909494701772928237304687500,113686837721616029736328125000
%N A130214 Order of modular group of degree 5^(n-1)+1.
%D A130214 E. Mathieu, Mémoire sur le nombre de valeurs que peut acquérir une fonction quand on y permute ses variables de toutes les manières possibles, Journ. de math. (2) 5 (1860), 9-42 (see p. 39).
%H A130214 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (130,-625).
%F A130214 a(n) = 5^(n - 1) (5^(2 n - 2) - 1)/2.
%F A130214 a(n) = 130*a(n-1)-625*a(n-2). G.f.: 60*x^2 / ((5*x-1)*(125*x-1)). - _Colin Barker_, Sep 02 2013
%t A130214 Table[5^(x - 1) (5^(2 x - 2) - 1)/2, {x, 1, 15}]
%t A130214 LinearRecurrence[{130,-625},{0,60},30] (* _Harvey P. Dale_, Aug 09 2023 *)
%Y A130214 Cf. A120689.
%K A130214 nonn,easy
%O A130214 1,2
%A A130214 _Artur Jasinski_, Aug 04 2007
%E A130214 More terms from _Colin Barker_, Sep 02 2013