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 A094625 #20 Feb 22 2024 09:02:11
%S A094625 0,2,22,33,242,343,2442,3443,24442,34443,244442,344443,2444442,
%T A094625 3444443,24444442,34444443,244444442,344444443,2444444442,3444444443,
%U A094625 24444444442,34444444443,244444444442,344444444443,2444444444442
%N A094625 Expansion of g.f. x*(2+22*x+11*x^2)/((x-1)*(1+x)*(10*x^2-1)).
%C A094625 Previous name: Palindromic sequence whose n-th term digits sum to 2n.
%H A094625 Paolo Xausa, <a href="/A094625/b094625.txt">Table of n, a(n) for n = 0..1000</a>
%H A094625 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,11,0,-10).
%F A094625 a(n) = 10^(n/2)*(31*sqrt(10)/180 + 11/9 - (31*sqrt(10)/180 - 11/9)*(-1)^n) - (-1)^n/2 - 35/18;
%F A094625 a(n) = A094623(n) + A094624(n).
%F A094625 G.f.: x*(2+22*x+11*x^2) / ( (x-1)*(1+x)*(10*x^2-1) ). - _R. J. Mathar_, Nov 27 2014
%F A094625 E.g.f.: (220*(cosh(sqrt(10)*x) - cosh(x)) + 31*sqrt(10)*sinh(sqrt(10)*x) - 130*sinh(x))/90. - _Stefano Spezia_, Feb 21 2024
%t A094625 LinearRecurrence[{0, 11, 0, -10}, {0, 2, 22, 33}, 30] (* _Paolo Xausa_, Feb 22 2024 *)
%Y A094625 Cf. A094623, A094624.
%K A094625 easy,nonn,base
%O A094625 0,2
%A A094625 _Paul Barry_, May 15 2004