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In the harmonic sequence 13,18,113, … which term is 1123?

 Dec 10, 2020
edited by Guest  Dec 10, 2020
 #1
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listfor(n,1, 25, (1 /(5*n - 2)))==(1 / 3, 1 / 8, 1 / 13, 1 / 18, 1 / 23, 1 / 28, 1 / 33, 1 / 38, 1 / 43, 1 / 48, 1 / 53, 1 / 58, 1 / 63, 1 / 68, 1 / 73, 1 / 78, 1 / 83, 1 / 88, 1 / 93, 1 / 98, 1 / 103, 1 / 108, 1 / 113, 1 / 118, 1 / 123).              1/123 would be the 25th term.

 Dec 10, 2020
 #2
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1/3, 1/8, 1/13 ......  

 

The formula for  the  nth term is

 

1 / [ 3 + 5(n -1) ] 

 

So

 

3 + 5(n -1)    =   123

 

5 ( n -1)   =120

 

n - 1  =   24

 

n =  25th term

 

 

cool cool cool

 Dec 10, 2020

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