%I #8 Nov 27 2022 00:19:26
%S 1,1,1,2,2,2,2,2,2,4,4,2,5,5,4,4,4,4,4,4,8,5,8,8,5,5,8,7,7,7,11,11,11,
%T 11,11,11,11,11,11,17,17,14,7,7,11,11,11,11,19,20,20,11,11,11,14,14,
%U 22,17,17,17,16,14,14,16,20,16,10,16,17,20,20,20,23
%N Cyclic token-passing numbers with pattern 121: players 1, 2, ..., n are seated around a table. Each has a penny. Player 1 passes a penny to player 2, who passes two pennies to player 3, who passes a penny to player 4. Player 4 passes a penny to player 5, who passes two pennies to player 6, who passes a penny to player 7 and so on, players passing 1,2,1,1,2,1,... pennies to the next player who still has some pennies. A player who runs out of pennies drops out of the game and leaves the table. Sequence gives number of players remaining when game reaches periodic state.
%D Suggested by 58th William Lowell Putnam Mathematical Competition, 1997, Problem A-2.
%H Sean A. Irvine <a href="https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a060/A060447.java">Java program</a> (github)
%H <a href="http://math.ucsd.edu/~pfitz/pastputnam.html">Putnam Mathematical Competitions</a>
%e a(10)=4 because 4 players (numbers 4, 6, 9, 10) remain.
%K easy,nonn,nice
%O 1,4
%A _Sen-Peng Eu_, Apr 08 2001
%E a(41) and a(51) corrected and more terms from _Sean A. Irvine_, Nov 20 2022