

A061798


Number of sums i^3 + j^3 that occur more than once for 1<=i<=j<=n.


2



0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 4, 4, 4, 4, 4, 5, 5, 7, 7, 8, 8, 8, 9, 10, 10, 10, 10, 10, 10, 10, 10, 12, 12, 12, 13, 13, 14, 15, 16, 16, 16, 17, 17, 19, 19, 19, 19, 20, 20, 20, 21, 23, 24, 24, 24, 25, 25, 25, 25
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OFFSET

1,16


LINKS



PROG

(PARI) a(n) = my(v=vector(2*n^3, i, 0)); for(i=1, n, for(j=i, n, v[i^3+j^3]+=1)); sum(i=1, #v, v[i]>1); \\ Seiichi Manyama, May 14 2024
(Ruby)
def A(n)
h = {}
(1..n).each{i
(i..n).each{j
k = i * i * i + j * j * j
if h.has_key?(k)
h[k] += 1
else
h[k] = 1
end
}
}
h.to_a.select{i i[1] > 1}.size
end
(1..n).map{i A(i)}
end


CROSSREFS



KEYWORD

nonn,changed


AUTHOR



STATUS

approved



