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A050440
Sixth-order composites.
3
56, 69, 77, 78, 84, 94, 100, 105, 106, 115, 124, 125, 126, 133, 140, 141, 145, 152, 156, 162, 164, 165, 170, 174, 183, 184, 188, 198, 202, 203, 206, 209, 212, 213, 218, 222, 231, 235, 236, 242, 243, 253, 256, 258, 259, 262, 264, 266, 270, 272, 278, 284
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(C(n)))))).
EXAMPLE
C(C(C(C(C(C(1)))))) = C(C(C(C(C(4))))) = C(C(C(C(9)))) = C(C(C(16))) = C(C(26)) = C(39) = 56. So 56 is in the sequence. So 77 is in the sequence.
MAPLE
C := remove(isprime, [$4..1000]): seq(C[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