A065457 Period of the flip-riffle shuffle function on a deck of 2n cards.

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

Offset: 1

Author

Russ Cox, Nov 19 2001

Keywords

• nonn

Comments

Duplicate of A055388? [Michel Marcus and Joerg Arndt, Jun 24 2013]

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

Examples

			The 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).