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A352244 Positive integers that can be expressed in at least two ways as (x-y)*(x^3-y^3).

%I A352244 #18 May 18 2024 15:06:46
%S A352244 57456,80752,124852,229957,355072,366471,630667,919296,1193200,
%T A352244 1292032,1316875,1371136,1823472,1997632,2036097,2687607,3679312,
%U A352244 4251871,4653936,5681152,5821552,5863536,6540912,8905456,8984196,10090672,10113012,10504375,10532592,10789632,10921456,14708736
%N A352244 Positive integers that can be expressed in at least two ways as (x-y)*(x^3-y^3).
%C A352244 Integers that appears at least twice in the A352242 triangle.
%H A352244 David A. Corneth, <a href="/A352244/b352244.txt">Table of n, a(n) for n = 1..12994</a> (terms <= 10^14)
%H A352244 David A. Corneth, <a href="/A352244/a352244.gp.txt">PARI program</a>
%e A352244 57456 is a term since it is A352242(17,5) as well as A352242(26,20).
%e A352244 A term (not necessarily the first) that occurs at least three times in A352242 is 1641000816 = A352242(221,65) = A352242(338,260) = A352242(1955,1943). - _Robert Israel_, May 17 2024
%o A352244 (PARI) row(n) = vector(n-1, k, (n-k)*(n^3-k^3));
%o A352244 lista(nn) = {my(list = List(), n=2); while (3*n*(n-1)+1 <= nn, my(rown = row(n)); for (k=1, #rown, if (rown[k] <= nn, listput(list, rown[k]))); n++;); listsort(list); my(res = List()); for (n=1, #list, if (#select(x->(x==list[n]), list) > 1, if (!vecsearch(Vec(res), list[n]), listput(res, list[n])));); Vec(res);}
%o A352244 (PARI) \\ See PARI link
%Y A352244 Cf. A352242, A352243.
%K A352244 nonn
%O A352244 1,1
%A A352244 _Michel Marcus_, Mar 09 2022, after a suggestion from Vincent Thill