This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A065457 #10 Mar 18 2018 04:06:13 %S A065457 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, %T A065457 52,20,18,58,60,6,12,66,22,70,18,20,30,78,54,82,8,28,22,12,10,36,48, %U A065457 30,100,102,12,106,36,36,28,44,12,24,110,20,100,14,14,130,18 %N A065457 Period of the flip-riffle shuffle function on a deck of 2n cards. %C A065457 Duplicate of A055388? [_Michel Marcus_ and _Joerg Arndt_, Jun 24 2013] %C A065457 The flip-riffle shuffle is a riffle shuffle but also turns the deck upside down. %e A065457 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. %Y A065457 Equals lcm(A002326(n), 2). %K A065457 nonn %O A065457 1,1 %A A065457 _Russ Cox_, Nov 19 2001