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A079486 Number of different solutions to a variant of the 3-ball tennis ball problem. 2

%I #3 Mar 31 2012 10:33:14

%S 3,15,103,879,8787,99061,1227369,16409937,233588249,3504149013,

%T 54963273921,895797910129

%N Number of different solutions to a variant of the 3-ball tennis ball problem.

%C You're given labeled balls three at time (labeled 1,2,3 then 4,5,6 etc.), choose two balls from those still on hand (including the three you've just been given) and throw the larger out the window onto the front lawn, the smaller onto the back lawn.

%D Larger numbers computed by Matt Richey.

%F a(n) is the number of 2 X n matrices of positive integers, with the numbers in each row and column increasing, the numbers in column k less than or equal to 3k and no number used more than once.

%Y Cf. A000108, A001764, A002293, A049235.

%K nonn

%O 1,1

%A _Barry Cipra_, Jan 19 2003

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Last modified March 29 06:57 EDT 2024. Contains 371265 sequences. (Running on oeis4.)