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A256607 Eventual period of 2^(2^k) mod n. 6
1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 4, 1, 2, 2, 1, 1, 1, 2, 6, 1, 2, 4, 10, 1, 4, 2, 6, 2, 3, 1, 4, 1, 4, 1, 2, 2, 6, 6, 2, 1, 4, 2, 3, 4, 2, 10, 11, 1, 6, 4, 1, 2, 12, 6, 4, 2, 6, 3, 28, 1, 4, 4, 2, 1, 2, 4, 10, 1, 10, 2, 12, 2, 6, 6, 4, 6, 4, 2, 12, 1, 18, 4, 20, 2, 1, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,7

COMMENTS

In other words, eventual period of 2 under the map x -> x^2 mod n.

a(n) is a divisor of A256608(n).

LINKS

Ivan Neretin, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A007733(A007733(n)).

EXAMPLE

For n=9 the map acts as follows: 2 -> 4 -> 7 -> 4 -> 7 and so on. This means the eventual period is 2, hence a(9)=2.

PROG

(Haskell)

a256607 = a007733 . fromIntegral . a007733

-- Reinhard Zumkeller, Apr 13 2015

CROSSREFS

Cf. A001146, A007733, A002326.

First differs from A256608 at n=43.

Column 2 of triangle in A279185.

Sequence in context: A230849 A135517 A280726 * A256608 A279186 A164799

Adjacent sequences:  A256604 A256605 A256606 * A256608 A256609 A256610

KEYWORD

nonn

AUTHOR

Ivan Neretin, Apr 04 2015

STATUS

approved

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Last modified June 16 05:18 EDT 2019. Contains 324145 sequences. (Running on oeis4.)