| 词条 | 206 (number) |
| 释义 |
| number = 206 | divisor = 1, 2, 103, 206 }} 206 (two hundred [and] six) is the natural number following 205 and preceding 207. In mathematics206 is both a nontotient and a noncototient.[1] 206 is an untouchable number.[2] It is the lowest positive integer (when written in English) to employ all of the vowels once only. The other numbers sharing this property are 230, 250, 260, 602, 640, 5000, 8000, 9000, 80,000 and 90,000.[3] 206 and 207 form the second pair of consecutive numbers (after 14 and 15) whose sums of divisors are equal.[4] There are exactly 206 different linear forests on five labeled nodes,[5] and exactly 206 regular semigroups of order four up to isomorphism and anti-isomorphism.[6] In scienceThere are 206 bones in the typical adult human body.[7] See also
References1. ^{{Cite OEIS|sequencenumber=A058763|name=Integers which are neither totient nor cototient}} {{Integers|2}}2. ^{{Cite web|url=https://oeis.org/A005114|title=Sloane's A005114 : Untouchable numbers|last=|first=|date=2016-04-18|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-04-18}} 3. ^{{Cite OEIS|sequencenumber=A058180|name=Numbers whose English names include all five vowels exactly once}} 4. ^{{Cite OEIS|sequencenumber=A002961|name=Numbers n such that n and n+1 have same sum of divisors}} 5. ^{{Cite OEIS|sequencenumber=A011800|name=Number of labeled forests of n nodes each component of which is a path}} 6. ^{{Cite OEIS|sequencenumber=A001427|name=Number of regular semigroups of order n, considered to be equivalent when they are isomorphic or anti-isomorphic (by reversal of the operator)}} 7. ^{{citation|title=Your 206 Bones, 32 Teeth, And Other Body Math|series=National Geographic Science Chapters|first=Robyn|last=O'Sullivan|publisher=National Geographic Books|year=2006|isbn=9780792259558}}. 1 : Integers |
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