OFFSET
1,16
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..1000
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
def A061798(n)
(1..n).map{|i| A(i)}
end
p A061798(80) # Seiichi Manyama, May 14 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Jun 22 2001
STATUS
approved