This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A101647 #20 Sep 13 2015 15:31:12 %S A101647 1,6,7,8,15,16,34 %N A101647 Atomic numbers of elements excluding metals, halogens, and noble gases in the periodic table. %C A101647 "Nonmetals" as normally understood in elementary chemistry. %C A101647 All nonmetals are sandwiched between the halogens and metalloids on the periodic table, with the exception of hydrogen, which is on the same group as the alkali metals. - Happelberg %C A101647 There may appear to be some disagreement in regards to the definition of nonmetals. This sequence appears on the cover of the Halka and Nordstrom book on nonmetals, and that book has eight chapters, the first seven of which are each devoted to an element identified by this sequence. %C A101647 The Baldwin book, on the other hand, flatly declares "All elements to the right of the stepped line [on the periodic table shown in that book] are nonmetals," meaning that the author also considers halogens and noble gases to be nonmetals. %C A101647 But then there is the Halka and Nordstrom book on halogens and noble gases, which says "The halogens ... are nonmetals, but have such special properties that they are given their own classification. The same is true for the noble gases." - _Alonso del Arte_, Apr 26 2011 %D A101647 Carol Baldwin, Nonmetals. Raintree (2006) p. 13 %D A101647 Monica Halka and Brian Nordstrom, Halogens and Noble Gases, Facts On File (2010), p. xiii %D A101647 Monica Halka and Brian Nordstrom, Nonmetals, Facts On File (2010) %D A101647 The New Encyclopaedia Britannica, 15th Edition, 1991, Volume 15 (Macropedia), Chemical Elements. %H A101647 Yinon Benton, <a href="http://www.chemicalelements.com/groups/nonmetals.html">Periodic Table: Non-Metals</a>, from ChemicalElements.com. %H A101647 Bodner Research Web, <a href="http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch10/non.php">The Chemistry Of Nonmetals</a>, from the Purdue University College of Science. %H A101647 Wikipedia, <a href="http://en.wikipedia.org/wiki/Nonmetal">Nonmetals</a>. %e A101647 Carbon is a nonmetal, and its atomic number is 6. %Y A101647 Cf. A099955 (alkali metals), A099956 (alkaline earth metals), A101648 (metalloids), A097478 (halogens), A018227 (noble gases), A101649 (poor metals). %K A101647 fini,full,nonn %O A101647 1,2 %A A101647 Robert Happelberg (roberthappelberg(AT)yahoo.com), Dec 10 2004