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A354266
Pairs of integers (s, t) such that 0 < s < t and gcd(s, t) > 1, where the pairs are generated by the boustrophedonic Cantor enumeration A319571.
1
2, 4, 2, 6, 3, 6, 2, 8, 4, 6, 2, 10, 3, 9, 4, 8, 2, 12, 4, 10, 6, 8, 3, 12, 5, 10, 6, 9, 2, 14, 4, 12, 6, 10, 2, 16, 3, 15, 4, 14, 6, 12, 8, 10, 2, 18, 4, 16, 5, 15, 6, 14, 8, 12, 3, 18, 6, 15, 7, 14, 9, 12, 2, 20, 4, 18, 6, 16, 8, 14, 10, 12, 2, 22, 3, 21
OFFSET
1,1
EXAMPLE
The sequence of pairs starts:
(2, 4), (2, 6), (3, 6), (2, 8), (4, 6), (2, 10), (3, 9), (4, 8), (2, 12), (4, 10),(6, 8), (3, 12), (5, 10), (6, 9), (2, 14), (4, 12), (6, 10), (2, 16), (3, 15),(4, 14), (6, 12), (8, 10), ...
PROG
(Julia)
function A354266List(upto)
L = Int[]
for n in 1:upto
d = div(isqrt(8n + 1) - 1, 2)
s = n - div(d*(d + 1), 2)
t = d - s
if s > 0 && s < t && gcd(s, t) > 1
push!(L, s)
push!(L, t)
end
end
L end
println(A354266List(303))
CROSSREFS
Cf. A319571.
Sequence in context: A230436 A105393 A182812 * A360005 A360457 A328985
KEYWORD
nonn
AUTHOR
Peter Luschny, May 21 2022
STATUS
approved