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A376881
Numbers that have exactly one Zumkeller divisor.
3
6, 18, 20, 28, 70, 88, 100, 104, 196, 272, 304, 368, 464, 496, 550, 572, 650, 836, 945, 968, 1184, 1312, 1352, 1376, 1430, 1504, 1575, 1696, 1870, 1888, 1952, 2002, 2090, 2205, 2210, 2470, 2530, 2584, 2990, 3128, 3190, 3230, 3410, 3465, 3496, 3770, 3944
OFFSET
1,1
COMMENTS
d is a Zumkeller divisor of n if and only if d is a divisor of n and is Zumkeller (A083207).
LINKS
FORMULA
If d is the only Zumkeller divisor of n and n is Zumkeller then d = n.
MAPLE
# The function 'isZumkeller' is defined in A376880.
zdiv := n -> select(isZumkeller, NumberTheory:-Divisors(n)):
select(n -> nops(zdiv(n)) = 1, [seq(1..4000)]);
CROSSREFS
Subsequence of A376880.
Sequence in context: A370865 A370863 A114452 * A253914 A283744 A108762
KEYWORD
nonn
AUTHOR
Peter Luschny, Oct 19 2024
STATUS
approved