A221616 - OEIS

%I #8 Jan 24 2013 14:57:24

%S 3,26,13,2,21,16,8,14,6,18,5,12,10,11,9,20,4,23,19,25,1,27,22,17,7,15,

%T 24

%N Permutation of the minimal 27 balls of a ball clock after a 12-hour period.

%C The clock has 3 bars with lengths 5, 11, 11. So the minimal number of balls is (5+11+11)+1=27. Use clock(0) PARI script to get the permutation.

%H dott. Roberto Gobbo, <a href="http://www-toys.science.unitn.it/toys/en-html/en-a-orologio.html">Roll-o-clock</a>

%H Adam Bowman, <a href="http://abowman.com/google-modules/ball-clock/">Ball Clock Gadget</a>

%o (PARI) clock(n) = {vb1 = []; vb2 = []; vb3 = []; nb1 = 5; nb2 = 12; nb3 = 12; nbmin = (nb1-1) + (nb2-1) + (nb3-1)+1; vbn = vector(nbmin+n,x,x); nbt = nb1*nb2*nb3; for (i=1, nbt, ib = vbn[1]; vbn = vector(length(vbn)-1, x, vbn[x+1]); vb1 = concat(vb1, ib); if (length(vb1) == nb1, vb2 = concat(vb2, ib); forstep(j=nb1-1, 1, -1, vbn = concat(vbn, vb1[j]);); vb1 = []; if (length(vb2) == nb2, vb3 = concat(vb3, ib); forstep(j=nb2-1, 1, -1, vbn = concat(vbn, vb2[j]);); vb2 = []; if (length(vb3) == nb3, vbn = concat(vbn, ib); forstep(j=nb3-1, 1, -1,vbn = concat(vbn, vb3[j]););vb3 = [];);););/* write("clock.log", "vb1=", vb1); write("clock.log", "vb2=", vb2); write("clock.log", "vb3=", vb3); write("clock.log", "vbN=", vbn); write("clock.log", "-----------");*/ ); return (vbn);}

%Y Cf. A221617.

%K nonn,fini,full

%O 1,1

%A _Michel Marcus_, Jan 21 2013