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 A052454 #27 Mar 18 2024 10:10:30
%S A052454 1,3,13,25,111,493,949,4215,18721,36037,160059,710905,1368457,6078027,
%T A052454 26995669,51965329,230804967,1025124517,1973314045,8764510719,
%U A052454 38927735977,74933968381,332820602355,1478228842609,2845517484433,12638418378771
%N A052454 Positive integer values of k such that 10*k^2 - 9 is a square.
%H A052454 Paolo Xausa, <a href="/A052454/b052454.txt">Table of n, a(n) for n = 1..1000</a>
%H A052454 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,38,0,0,-1).
%F A052454 a(n) = 38*a(n-3)-a(n-6).
%F A052454 G.f.: x*(1-x)*(1+4*x+17*x^2+4*x^3+x^4)/(1-38*x^3+x^6). [_Colin Barker_, Jun 13 2012]
%e A052454 25 is a term of the sequence since 10*25^2-9 = 6241 = 79^2.
%t A052454 LinearRecurrence[{0, 0, 38, 0, 0, -1}, {1, 3, 13, 25, 111, 493}, 50] (* _Paolo Xausa_, Mar 18 2024 *)
%Y A052454 Cf. A077442, A082651, A221874.
%K A052454 nonn,easy
%O A052454 1,2
%A A052454 _John W. Layman_, May 20 2003
%E A052454 More terms from _Bruno Berselli_, Jan 29 2013