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A048669 Jacobsthal function: maximal distance between integers relatively prime to n. +0
9
1, 2, 2, 2, 2, 4, 2, 2, 2, 4, 2, 4, 2, 4, 3, 2, 2, 4, 2, 4, 3, 4, 2, 4, 2, 4, 2, 4, 2, 6, 2, 2, 3, 4, 3, 4, 2, 4, 3, 4, 2, 6, 2, 4, 3, 4, 2, 4, 2, 4, 3, 4, 2, 4, 3, 4, 3, 4, 2, 6, 2, 4, 3, 2, 3, 6, 2, 4, 3, 6, 2, 4, 2, 4, 3, 4, 3, 6, 2, 4, 2, 4, 2, 6, 3, 4, 3, 4, 2, 6, 3, 4, 3, 4, 3, 4, 2, 4, 3, 4, 2, 6, 2, 4, 5 (list; graph; listen)
OFFSET

1,2

COMMENT

Differs from A070194 by 1 at the primes. - T. D. Noe, Mar 21 2007

REFERENCES

E. Jacobsthal, Uber Sequenzen ganzer Zahlen, von denen keine zu n teilerfremd ist, I, II, III. Norske Videnskabsselskab Forhdl., 33, 1960, 117-139

P. Erdos, On the integers relatively prime to n and on a number theoretic function considered by Jacobsthal. Math. Scand., 10, 1962, 163-170

H. Iwaniec, On the problem of Jacobsthal. Demo. Math., 11, 1978, 225-231

LINKS

T. D. Noe, Table of n, a(n) for n=1..10000

EXAMPLE

a(6)=4 because the gap between 1 and 5, both being relatively prime to 6, is maximal and 5-1 = 4.

CROSSREFS

Cf. A048670. Essentially same as A049298. See A132468 for another version.

Cf. A070971.

Adjacent sequences: A048666 A048667 A048668 this_sequence A048670 A048671 A048672

Sequence in context: A122066 A053238 A058263 this_sequence A158522 A034444 A073180

KEYWORD

nonn,easy,nice

AUTHOR

Jan Kristian Haugland (jankrihau(AT)hotmail.com)

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Last modified November 8 07:45 EST 2009. Contains 166143 sequences.


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