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A048983 As n runs through composite numbers, a(n) = number of composite d < n such that GCD(d,n) = 1. 1
0, 0, 0, 2, 1, 0, 1, 3, 2, 0, 1, 5, 3, 0, 11, 4, 9, 4, 0, 5, 10, 6, 14, 2, 7, 13, 5, 1, 7, 11, 9, 2, 27, 6, 18, 10, 3, 25, 9, 21, 13, 1, 13, 19, 14, 31, 4, 14, 26, 7, 5, 16, 20, 16, 40, 5, 11, 32, 19, 3, 42, 20, 34, 18, 2, 49, 21, 37, 23, 49, 9, 18 (list; graph; refs; listen; history; internal format)
OFFSET

0,4

EXAMPLE

9 is 4th composite number, GCD(9,4)=GCD(9,8)=1, so a(4) = 2.

CROSSREFS

Cf. A000010, A048984.

Sequence in context: A100995 A129353 A136566 * A118344 A119270 A175804

Adjacent sequences:  A048980 A048981 A048982 * A048984 A048985 A048986

KEYWORD

easy,nonn

AUTHOR

Naohiro Nomoto (6284968128(AT)geocities.co.jp)

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Last modified February 14 05:35 EST 2012. Contains 205570 sequences.