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 A077448 #23 Mar 25 2024 13:12:35
%S A077448 1,36,100,196,225,441,484,676,1089,1156,1225,1444,1521,2116,2601,3025,
%T A077448 3249,3364,3844,4225,4761,5476,5929,6724,7225,7396,7569,8281,8649,
%U A077448 8836,9025,11236,12321,13225,13924,14161,14884,15129,16641,17689,17956
%N A077448 Numbers k such that Sum_{d|k} mu(d)*mu(k/d)^2 = +1.
%H A077448 Amiram Eldar, <a href="/A077448/b077448.txt">Table of n, a(n) for n = 1..10000</a>
%F A077448 a(n) = A030229(n)^2.
%F A077448 Sum_{n>=1} 1/a(n) = 21/(2*Pi^2). - _Amiram Eldar_, Jul 16 2020
%t A077448 Select[Range[135], MoebiusMu[#] == 1 &]^2 (* _Amiram Eldar_, Jul 16 2020 *)
%o A077448 (PARI) is(n)=if(!issquare(n,&n),return(0)); my(f=factor(n)[,2]); if(n>1, #f%2==0 && vecmax(f)==1, n==1) \\ _Charles R Greathouse IV_, Oct 16 2015
%Y A077448 Cf. A008683, A030229, A077438, A085986 (subsequence).
%K A077448 nonn
%O A077448 1,2
%A A077448 _Benoit Cloitre_, Nov 30 2002