monarch,
The approach I used is that each term was being multiplied by some number. There were two patterns of multiples woven together. One pattern was constant - x 2. The other depends on the previous value (prev / 2). 
1 x 5     = 5    # pattern 1, no prev value so start with 5
5 x 2     = 10   # pattern 2, constant
10 x 2.5  = 25   # pattern 1, prev value 5 / 2
25 x 2    = 50   # pattern 2, constant
50 x 1.25 = 62.5 # pattern 1, prev value 2.5 / 2

[download]

Cheers - L~R

In reply to Re^3: A script to determine the next number in a sequence by Limbic~Region
in thread A script to determine the next number in a sequence by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.