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seq

by maihuna » Sat Apr 09, 2011 1:53 pm
what is the 60th term in following sequence : 1, 2, 4, 7, 11, 16, 22, ...

1671
1760
1761
1771
1821
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by anshumishra » Sat Apr 09, 2011 2:02 pm
maihuna wrote:what is the 60th term in following sequence : 1, 2, 4, 7, 11, 16, 22, ...

1671
1760
1761
1771
1821
t(1) = 1
t(2) = t(1) + 1
t(3) = t(2) + 2 = t(1) + (1+2)
t(4) = t(3) + 3 = t(1) + (1+2+3)
.........

The nth term for this sequence , t(n) = t(1) + [1+2+3+...+(n-1)]
So, t(60) = t(1) + (1+2+3+...+59) = 1+ 59*60/2 = 1771
Thanks
Anshu

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