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A072357 Cube-free non-squares having exactly one square in their factorization. +0
1
12, 18, 20, 28, 44, 45, 50, 52, 60, 63, 68, 75, 76, 84, 90, 92, 98, 99, 116, 117, 124, 126, 132, 140, 147, 148, 150, 153, 156, 164, 171, 172, 175, 188, 198, 204, 207, 212, 220, 228, 234, 236, 242, 244, 245, 260, 261, 268, 275, 276, 279, 284, 292, 294, 306, 308 (list; graph; listen)
OFFSET

1,1

COMMENT

n such that A001222(n) - A001221(n) = 1 and A001221(n)>1.

EXAMPLE

a(14) = 84 = 7*3*2^2; the following numbers are not terms: 36=6^2, as it is a square; 54=2*3^3, as it is not cube-free; 42=2*3*7, as there is no prime square; 72=2*6^2, as 72 has two prime square divisors: 2^2 and 3^2.

CROSSREFS

Cf. A054753, A060687, A067259, A004709.

Sequence in context: A070011 A084679 A072588 this_sequence A054753 A098899 A098770

Adjacent sequences: A072354 A072355 A072356 this_sequence A072358 A072359 A072360

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller (reinhard.zumkeller(AT)lhsystems.com), Jul 18 2002

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Last modified August 29 17:54 EDT 2008. Contains 143238 sequences.


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