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A065457 Period of the flip-riffle shuffle function on a deck of 2n cards. 0
2, 2, 4, 6, 6, 10, 12, 4, 8, 18, 6, 22, 20, 18, 28, 10, 10, 12, 36, 12, 20, 14, 12, 46, 42, 8, 52, 20, 18, 58, 60, 6, 12, 66, 22, 70, 18, 20, 30, 78, 54, 82, 8, 28, 22, 12, 10, 36, 48, 30, 100, 102, 12, 106, 36, 36, 28, 44, 12, 24, 110, 20, 100, 14, 14, 130, 18 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

The flip-riffle shuffle is a riffle shuffle but also turns the deck upside down.

EXAMPLE

flip-riffle shuffle on 6 cards is [1,2,3,4,5,6] -> [6,3,5,2,4,1]. The period of this function is 4, hence a(3) = 4.

CROSSREFS

Equals LCM(A002326(n), 2)

Sequence in context: A137268 A008130 A055388 * A000784 A092991 A102425

Adjacent sequences:  A065454 A065455 A065456 * A065458 A065459 A065460

KEYWORD

nonn

AUTHOR

Russ Cox (rsc(AT)swtch.com) Nov 19, 2001

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Last modified February 15 16:56 EST 2012. Contains 205825 sequences.