411 REFERENCE · Wiktionary
Kempner series
Reference material by Wiktionary contributors. This retains its source identity and is not 411 news reporting.
English
Etymology
The series was first studied by Aubrey J. Kempner in 1914.
Noun
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en math A modification of the harmonic series, formed by omitting all terms whose denominator expressed in base 10 contains the digit 9.
en eponyms