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 A273375 #33 Feb 21 2025 18:05:30
%S A273375 4,64,144,324,484,784,1024,1444,1764,2304,2704,3364,3844,4624,5184,
%T A273375 6084,6724,7744,8464,9604,10404,11664,12544,13924,14884,16384,17424,
%U A273375 19044,20164,21904,23104,24964,26244,28224,29584,31684,33124,35344,36864,39204,40804,43264
%N A273375 Squares ending in digit 4.
%H A273375 Seiichi Manyama, <a href="/A273375/b273375.txt">Table of n, a(n) for n = 1..10000</a>
%H A273375 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,2,-2,-1,1).
%F A273375 G.f.: 4*x*(1 + 15*x + 18*x^2 + 15*x^3 + x^4) /((1+x)^2*(1-x)^3).
%F A273375 a(n) = 4*A047209(n)^2 = (10*n + (-1)^n - 5)^2/4.
%F A273375 Sum_{n>=1} 1/a(n) = 2*Pi^2/(25*(5-sqrt(5))). - _Amiram Eldar_, Feb 16 2023
%F A273375 E.g.f.: (4 - 5*x + 25*x^2)*cosh(x) + (9 + 5*x + 25*x^2)*sinh(x) - 4. - _Stefano Spezia_, Feb 21 2025
%t A273375 Table[(10 n + (-1)^n - 5)^2/4, {n, 1, 50}] (* or *) LinearRecurrence[{1, 2, -2, -1, 1}, {4, 64, 144, 324, 484}, 50]
%t A273375 Select[Range[200]^2,Mod[#,10]==4&] (* or *) LinearRecurrence[{1,1,-1},{2,8,12},40]^2(* _Harvey P. Dale_, Aug 06 2017 *)
%o A273375 (Magma) /* By definition: */ [n^2: n in [0..200] | Modexp(n, 2, 10) eq 4];
%o A273375 (Magma) [(10*n+(-1)^n-5)^2/4: n in [1..50]];
%Y A273375 Cf. A000290, A047209.
%Y A273375 Cf. A017317 (numbers ending in 4), A017319 (cubes ending in 4).
%Y A273375 Cf. similar sequences listed in A273373.
%K A273375 nonn,base,easy
%O A273375 1,1
%A A273375 _Vincenzo Librandi_, May 24 2016
%E A273375 Edited by _Bruno Berselli_, May 24 2016