14 lines
1 KiB
Rexx
14 lines
1 KiB
Rexx
/*REXX pgm finds N terms of the Sylvester's sequence & the sum of the their reciprocals.*/
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parse arg n . /*obtain optional argument from the CL.*/
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if n=='' | n=="," then n= 10 /*Not specified? Then use the default.*/
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numeric digits max(9, 2**(n-7) * 13 + 1) /*calculate how many dec. digs we need.*/
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@.0= 2 /*the value of the 1st Sylvester number*/
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$= 0
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do j=0 for n; jm= j - 1 /*calculate the Sylvester sequence. */
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if j>0 then @.j= @.jm**2 - @.jm + 1 /*calculate a Sylvester sequence num.*/
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say 'Sylvester('j") ──► " @.j /*display the Sylvester index & number.*/
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$= $ + 1 / @.j /*add its reciprocal to the recip. sum.*/
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end /*j*/
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say /*stick a fork in it, we're all done. */
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numeric digits digits() - 1
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say 'sum of the first ' n " reciprocals using" digits() 'decimal digits: ' $ / 1
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