This expression above is basically what I posted to the seqfan mailing list:
Wikipedia Möbius function
Link to Wikipedia revision history:
Wikipedia, Möbius function, difference between revisions 1
Using the six first terms (on the right hand side) I get 14 accurate decimals, of 14 possible in a spreadsheet, in the interval -0.5 to +0.5. The technique for inverting triangular matrices as a binomial series, which is the basis for this formula, was learned together with Gary W. Adamson.
This expression above simplifies to:
Keywords: Mobius function, power series, binomial series.