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A285181 Index m such that A280864(m) = n^2.

%I A285181 #16 Apr 12 2025 01:40:13
%S A285181 1,3,10,13,35,33,48,65,94,100,86,142,144,157,148,258,399,300,453,395,
%T A285181 319,483,358,565,720,665,845,755,893,864,924,1009,1033,1133,1216,1262,
%U A285181 1293,1437,1375,1603,1724,1720,2015,1898,2154,2078,2071,2257,2547,2422,2687,2618,2714,2807,3055,3034
%N A285181 Index m such that A280864(m) = n^2.
%H A285181 Michael De Vlieger, <a href="/A285181/b285181.txt">Table of n, a(n) for n = 1..4107</a> (first 996 terms from N. J. A. Sloane).
%p A285181 # Let b280864 contain a list of the terms of A280864
%p A285181 a:=[];
%p A285181 for n from 1 to 500 do
%p A285181 if member(n^2, b280864,'p') then a:=[op(a),p]; else  \
%p A285181 lprint("error",n); break; fi; od:
%p A285181 a;
%t A285181 nn = 3600; c[_] := False; m[_] := 1;
%t A285181 Set[{i, j, s, t, c[1], c[2]}, {1, 2, {}, {2}, True, True}];
%t A285181 s = Sort[{{1, 1}}~Join~Reap[Do[
%t A285181   r = Times @@ Select[t, FreeQ[s, #] &];
%t A285181   v = Times @@ Intersection[s, t];
%t A285181   k = m[r]; While[Or[c[#], ! CoprimeQ[v, #]] &[k*r], k++]; k *= r;
%t A285181   Set[{c[k], i, j, s, t}, {True, j, k, t, FactorInteger[k][[All, 1]]}];
%t A285181   If[k == u, While[c[u], u++]]; While[c[r*m[r]], m[r]++];
%t A285181   If[IntegerQ@ Sqrt[k], Sow[{Sqrt[k], n}]], {n, 3, nn}] ][[-1, 1]] ];
%t A285181 s[[;; #, -1]] &@ LengthWhile[Differences@ s[[;; , 1]], # == 1 &] (* _Michael De Vlieger_, Apr 11 2025 *)
%Y A285181 Cf. A280864.
%K A285181 nonn
%O A285181 1,2
%A A285181 _N. J. A. Sloane_, Apr 14 2017