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A036116
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Numbers n such that the number of distinct primes dividing n is a square.
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3
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1, 2, 3, 4, 5, 7, 8, 9, 11, 13, 16, 17, 19, 23, 25, 27, 29, 31, 32, 37, 41, 43, 47, 49, 53, 59, 61, 64, 67, 71, 73, 79, 81, 83, 89, 97, 101, 103, 107, 109, 113, 121, 125, 127, 128, 131, 137, 139, 149, 151, 157, 163, 167, 169, 173, 179, 181, 191, 193, 197, 199, 210, 211, 223, 227, 229, 233, 239, 241, 243, 251, 256, 257, 263, 269, 271, 277, 281
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OFFSET
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1,2
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LINKS
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EXAMPLE
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8 = 2^3 is divisible by just one (distinct) prime, 2 and 1 is a square, so 8 is in the sequence.
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MAPLE
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readlib(issqr): with(numtheory): select(x->issqr(nops(factorset(x))), [ seq(n, n=1..300) ]);
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MATHEMATICA
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PROG
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CROSSREFS
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Differs from A000961 at a(62) = 210, etc.
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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