__,__,__,48,100,180,
294,448,648,__,__,__,.......Find the three numbers before and after given numbers in the series.
(In reply to
re: Solution by differences by Hugo)
The numbers that pop out of the differencing can be used with binominal coefficients to get the formula straight away. The formula would be 4 x (n choose 1) + 10 x (n choose 2) + 6 x (n choose 3) where the third term is 48. This reduces to n x (n+1) x (n+1). There is also a component, 0 x (n choose 0), that can be dropped, due to the "zeroeth" term of the series being zero.
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Posted by bernie
on 2005-04-28 22:30:58 |
re(2): Solution by differences
