cp's OEIS Frontend

A321492 Numbers that can be written as (x + y)(x^2 + y^2), x > y > 0, in at least two ways.

%I A321492 #12 Nov 22 2018 18:48:33
%S A321492 12325,98600,117720,146705,206312,263840,332775,378505,400945,500200,
%T A321492 651456,687245,734400,741845,773800,788800,799240,941760,1173640,
%U A321492 1327360,1533195,1540625,1650496,1735105,1836680,1943240,2048320,2050880,2110720,2217280,2662200,2704360,2965685
%N A321492 Numbers that can be written as (x + y)(x^2 + y^2), x > y > 0, in at least two ways.
%C A321492 See A321491 for numbers of the form (x+y)(x^2+y^2) = A321490(x,y) with x > y > 0.
%H A321492 Geoffrey B. Campbell, <a href="https://www.linkedin.com/groups/4510047/4510047-6434736765982072833">(m+n)(m²+n²) in two different ways</a>, LinkedIn Number Theory Group, Aug. 2018
%e A321492 12325 = (13+16)(13^2+16^2) = (3+22)(3^2+22^2).
%e A321492 98600 = (26+32)(26^2+32^2) = (6+44)(6^2+44^2).
%e A321492 117720 = (21+39)(21^2+39^2) = (8+46)(8^2+46^2).
%e A321492 146705 = (24+41)(24^2+41^2) = (14+47)(14^2+47^2).
%e A321492 206312 = (15+53)(15^2+53^2) = (32+42)(32^2+42^2).
%e A321492 263840 = (6+62)(6^2+62^2) = (33+47)(33^2+47^2).
%o A321492 (PARI) A321492_list(L=1e6)={my(S=[],T=List(),t);for(m=2,sqrtn(L,3),while(#S&&S[1]<=m^3, S=S[^1]); for(n=1,m-1,if(L<t=(m+n)*(m^2+n^2),next(2),setsearch(S,t),listput(T,t);S=setminus(S,[t]),S=setunion(S,[t]))));Set(T)}
%Y A321492 Cf. A321490, A321491.
%K A321492 nonn
%O A321492 1,1
%A A321492 Geoffrey B. Campbell and _M. F. Hasler_, Nov 22 2018