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 A219239 #16 Oct 11 2019 03:03:38 %S A219239 4,10,16,22,28,30,36,40,48,52,56,58,70,78,84,90,100,102,110,128,132, %T A219239 134,146,154,164,176,208,252 %N A219239 Double magic numbers (in physics). %C A219239 For the magic numbers see A018226. %C A219239 An atomic nucleus is called double magic if Z (number of protons in an atomic nucleus, atomic number) and N (number of neutrons) are both magic numbers. The nucleon or mass number (forget the Z electrons) is A = Z + N. %C A219239 Each number a(n) is obtained in only one way as a sum of two (possibly equal) magic numbers. Only 28 is magic and double magic. %H A219239 Wikipedia, <a href="https://en.wikipedia.org/wiki/Magic_number_%28physics%29#Double_magic">Double magic</a>. %H A219239 Wikipedia, <a href="https://en.wikipedia.org/wiki/List_of_nuclides">List of Nuclides</a>. %F A219239 a(n) is the sum of two numbers from [2, 8, 20, 28, 50, 82, 126] (the magic numbers A018226). %e A219239 Tin-132 is a double magic radionuclide (unstable isotope) with nucleon number A = 132 = a(21), Z = 50 and N = 82. Similarly for tin-100 with Z = N = 50. The stable primordial nuclide barium-132 is not double magic, because it has Z = 56 and N = 76. %Y A219239 Cf. A018226, A033547. %K A219239 nonn,fini %O A219239 1,1 %A A219239 _Wolfdieter Lang_, Dec 12 2012