R-188.8.131.52 Compounds containing an unbranched chain of alternating atom terminated by two identical atoms of the element coming later in Table 3 (see R-184.108.40.206) may be named by citing successively a multiplying prefix denoting the number of atoms of the terminating element followed by the "a" term of that element (see R-9.3), then the "a" term of the other element of the chain and the ending "-ane". The terminal letter "a" of an "a" term is elided when followed by a vowel; the terminal vowel of a numerical prefix is not elided even when the "a" term begins with the same vowel.
Example to R-220.127.116.11
Examples to R-18.104.22.168
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