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A050439
Fifth-order composites.
8
39, 49, 55, 56, 60, 69, 74, 77, 78, 84, 93, 94, 95, 100, 105, 106, 110, 115, 119, 124, 125, 126, 130, 133, 140, 141, 145, 152, 155, 156, 159, 162, 164, 165, 170, 174, 180, 183, 184, 188, 189, 198, 201, 202, 203, 206, 207, 209, 212, 213, 218, 222, 225, 231
OFFSET
1,1
LINKS
N. Fernandez, An order of primeness [cached copy, included with permission of the author]
FORMULA
Let C(n) be the n-th composite number, with C(1)=4. Then these are numbers C(C(C(C(C(n))))).
EXAMPLE
C(C(C(C(C(8))))) = C(C(C(C(15)))) = C(C(C(25))) = C(C(38)) = C(55) = 77. So 77 is in the sequence.
MAPLE
C := remove(isprime, [$4..1000]): seq(C[C[C[C[C[n]]]]], n=1..100);
KEYWORD
easy,nonn
AUTHOR
Michael Lugo (mlugo(AT)thelabelguy.com), Dec 22 1999
EXTENSIONS
More terms from Asher Auel Dec 15 2000
STATUS
approved