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A050438
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Fourth-order composites.
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3
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26, 33, 38, 39, 42, 49, 52, 55, 56, 60, 68, 69, 70, 74, 77, 78, 80, 84, 88, 93, 94, 95, 98, 100, 105, 106, 110, 115, 118, 119, 121, 124, 125, 126, 130, 133, 138, 140, 141, 145, 146, 152, 154, 155, 156, 159, 160, 162, 164, 165, 170, 174, 176, 180, 183, 184
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OFFSET
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1,1
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LINKS
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Table of n, a(n) for n=1..56.
N. Fernandez, An order of primeness, F(p)
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FORMULA
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Let C(n) be the n-th composite number, with C(1)=4. Then these are numbers C(C(C(C(n)))).
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EXAMPLE
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C(C(C(C(8)))) = C(C(C(15))) = C(C(25)) = C(38) = 55. So 55 is in the sequence.
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MAPLE
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C := remove(isprime, [$4..1000]): seq(C[C[C[C[n]]]], n=1..100);
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CROSSREFS
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A049076-A049081, A006450, A050435, A050436, A050439, A050440.
Sequence in context: A153224 A177210 A050770 * A047822 A048126 A080932
Adjacent sequences: A050435 A050436 A050437 * A050439 A050440 A050441
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KEYWORD
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easy,nonn
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AUTHOR
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Michael Lugo (mlugo(AT)thelabelguy.com), Dec 22 1999
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EXTENSIONS
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More terms from Asher Auel (asher.auel(AT)reed.edu) Dec 15 2000
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STATUS
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approved
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