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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..54.

N. Fernandez, An order of primeness, F(p)

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);

CROSSREFS

Cf. A049076-A049081, A006450, A050435, A050436, A050438, A050440.

Sequence in context: A143746 A064399 A235151 * A199993 A181488 A020305

Adjacent sequences:  A050436 A050437 A050438 * A050440 A050441 A050442

KEYWORD

easy,nonn

AUTHOR

Michael Lugo (mlugo(AT)thelabelguy.com), Dec 22 1999

EXTENSIONS

More terms from Asher Auel (asher.auel(AT)reed.edu) Dec 15 2000

STATUS

approved

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Last modified October 18 00:55 EDT 2019. Contains 328135 sequences. (Running on oeis4.)