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

1,1

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.

Links

Table of n, a(n) for n=1..67.

Example

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).

Sequence in context: A137268 A008130 A055388 * A280366 A000784 A355573

Adjacent sequences: A065454 A065455 A065456 * A065458 A065459 A065460

Keyword

nonn

Author

Russ Cox, Nov 19 2001

Status

approved