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 A122995 #22 Mar 11 2017 08:55:13
%S A122995 1,5,30,155,905,4780,27405,146905,832030,4504655,25305405,137921780,
%T A122995 770556905,4218601405,23482524030,128947559155,716010659905,
%U A122995 3939699638780,21839966136405,120332457105905,666331610516030,3674643038163655,20332933301064405,112199009255155780
%N A122995 Expansion of x*(1+4*x)/(1-x-25*x^2).
%C A122995 The sequence can also be generated by adding of the top-row elements of the (n-1)st power of the matrix [[0,1],[1,1/5]] and multiplying with 5^(n-1).
%H A122995 Nathaniel Johnston, <a href="/A122995/b122995.txt">Table of n, a(n) for n = 1..500</a>
%H A122995 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (1,25)
%F A122995 a(n) = a(n-1)+25*a(n-2). [_Philippe Deléham_, Mar 26 2009]
%F A122995 a(n) = A122999(n-1) + 4*A122999(n-2). [_R. J. Mathar_, Aug 12 2009]
%F A122995 a(n) = (1/2+9*sqrt(101)/202)*(1/2+sqrt(101)/2)^(n-1) + (1/2-9*sqrt(101)/202)*(1/2-sqrt(101)/2)^(n-1). [_Antonio Alberto Olivares_, Jun 07 2011]
%t A122995 M := {{0, 1}, {1, 1/5}}; v[1] = {1, 1}; v[n_] := v[n] = M.v[n - 1]; a = Table[v[n][[1]]*5^(n - 1), {n, 1, 30}]
%t A122995 LinearRecurrence[{1,25},{1,5},30] (* _Harvey P. Dale_, Mar 11 2017 *)
%o A122995 (PARI) Vec(x*(1+4*x)/(1-x-25*x^2) + O(x^30)) \\ _Michel Marcus_, Jan 28 2015
%Y A122995 Cf. A026597.
%K A122995 nonn,easy
%O A122995 1,2
%A A122995 _Roger L. Bagula_, Sep 22 2006
%E A122995 Replaced definition by a specific one - The Assoc. Eds. of the OEIS, Jun 07 2010
%E A122995 More terms from _Michel Marcus_, Jan 28 2015