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 A210983 #21 Sep 05 2012 13:31:13 %S A210983 1,3,4,7,8,10,14,16,17,20,25,28,29,31,35,41,45,47,48,51,56,63,68,71, %T A210983 72,74,78,84,92,98,102,104,105,108,113,120,129,136,141,144,145,147, %U A210983 151,157,165,175,183,189,193,195,196,199,204,211,220,231 %N A210983 Total number of pairs of states of the first n subshells of the nuclear shell model in which the subshells are ordered by energy level in increasing order. %C A210983 Additional comments from _Omar E. Pol_, Sep 02 2012: (Start) %C A210983 Q: What are energy levels? %C A210983 A: See the link sections of A212122, A213362, A213372. For example, see this link related to A213372: http://www.flickr.com/photos/mitopencourseware/3772864128/in/set-72157621892931990 %C A210983 Q: What defines the order in A212121? %C A210983 A: The order of A212121 is defined by A212122. %C A210983 Note that there are at least five versions of the nuclear shell model in the OEIS: %C A210983 Goeppert-Mayer (1950): A212012, A004736, A212013, A212014. %C A210983 Goeppert-Mayer, Jensen (1955): A212122, A212121, A212123, A212124. %C A210983 Talmi (1993): A213362, A213361, A213363, A213364. %C A210983 Meyerhof: A213372, A213371, A213373, A213374. %C A210983 For another version: A162630, A130517, A210983, A210984. %C A210983 Each version is represented by four sequences: the first sequence is the main entry. %C A210983 (End) %C A210983 For additional information see A162630. %F A210983 a(n) = A210984(n)/2. %e A210983 Example 1: written as a triangle in which row i is related to the (i-1)st level of nucleus, the sequence begins: %e A210983 1; %e A210983 3, 4; %e A210983 7, 8, 10; %e A210983 14, 16, 17, 20; %e A210983 25, 28, 29, 31, 35; %e A210983 41, 45, 47, 48, 51, 56; %e A210983 63, 68, 71, 72, 74, 78, 84; %e A210983 92, 98, 102, 104, 105, 108, 113, 120; %e A210983 129, 136, 141, 144, 145, 147, 151, 157, 165; %e A210983 175, 183, 189, 193, 195, 196, 199, 204, 211, 220; %e A210983 ... %e A210983 Column 1 gives positive terms of A004006. Right border gives positives terms of A000292. %e A210983 Example 2: written as an irregular triangle in which row j is related to the j-th shell of nucleus. Note that in this case row 4 has only one term. Triangle begins: %e A210983 1; %e A210983 3, 4; %e A210983 7, 8, 10; %e A210983 14; %e A210983 16, 17, 20, 25; %e A210983 28, 29, 31, 35, 41; %e A210983 45, 47, 48, 51, 56, 63; %e A210983 68, 71, 72, 74, 78, 84, 92; %e A210983 98, 102, 104, 105, 108, 113, 120, 129; %e A210983 136, 141, 144, 145, 147, 151, 157, 165, 175; %e A210983 183, 189, 193, 195, 196, 199, 204, 211, 220, 231; %e A210983 ... %Y A210983 Partial sums of A130517 (when that sequence is regarded as a flattened triangle). Other versions are A212013, A212123, A213363, A213373. %Y A210983 Cf. A000292, A004006, A162630, A210984 %K A210983 nonn,tabf %O A210983 1,2 %A A210983 _Omar E. Pol_, Jul 14 2012