cp's OEIS Frontend

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.

Showing 1-3 of 3 results.

A160914 Extended s-block elements for Janet table.

Original entry on oeis.org

1, 2, 3, 4, 11, 12, 19, 20, 37, 38, 55, 56, 87, 88, 119, 120, 169, 170, 219, 220, 291, 292, 363, 364, 461, 462, 559, 560, 687, 688, 815, 816, 977, 978, 1139, 1140, 1339, 1340, 1539, 1540, 1781, 1782, 2023, 2024, 2311, 2312, 2599, 2600, 2937, 2938, 3275, 3276
Offset: 1

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Author

Paul Curtz, Oct 15 2011

Keywords

Comments

See A168342. Must be included in A167268. From right to left, first vertical is A168380 from 1 to 8. Second vertical is A168380-1. In (1) page 12, introducing elements 93 to 120, Janet says that there is a probable 8th row. For row 8, he proposes, like for row 7, 32 elements (89 to 120). Page 16 he presents 4 blocks: first has 2*8 elements, second: 6*6, third: 10*4, fourth: 14*2. Today, blocks are s,p,d,f for Mendeleyev-Moseley-Seaborg 118 elements periodic table. See (2), (3), A173592 and A138509. In 1927, only 88 on the first 92 elements were known; 41 (1937 discovered), 61 (1947), 85 (1940) and 87 (1939) were missing. Since 2010 (117 discovered) the first 118 elements are known. Janet predicted only 120 elements.

Examples

			The following is an s-block, 2*8=16 elements, i.e., a(n) written vertically, after p-block, 6*6, (A138469).
                          1   2
                          3   4
5   6   7   8   9   10   11  12
13  14  15  16  17  18   19  20
31  32  33  34  35  36   37  38
49  50  51  52  53  54   55  56
81  82  83  84  85  86   87  88
113 114 115 116 117 118  119 120
		

References

  • Charles JANET, La structure du Noyau de l'atome,considérée dans la Classification périodique, des éléments chimiques, 1927 (Novembre) N. 2 Beauvais, 67 pages, 3 leaflets.

Crossrefs

Cf. A099955.

A271996 The crystallogen sequence (a(n) = A018227(n)-4).

Original entry on oeis.org

6, 14, 32, 50, 82, 114, 164, 214, 286, 358, 456, 554, 682, 810, 972, 1134, 1334, 1534, 1776, 2018, 2306, 2594, 2932, 3270, 3662, 4054, 4504, 4954, 5466, 5978, 6556, 7134, 7782, 8430, 9152, 9874, 10674, 11474, 12356, 13238, 14206, 15174, 16232, 17290, 18442
Offset: 2

Views

Author

Natan Arie Consigli, Jun 18 2016

Keywords

Comments

Terms up to 114 are the atomic numbers of the elements of group 14 in the periodic table. Those elements are also called crystallogens.

Crossrefs

Programs

  • Mathematica
    Table[(6*(-9+(-1)^n)+(25+3*(-1)^n)*n+12*n^2+2*n^3)/12, {n, 2, 10}] (* or *) LinearRecurrence[{2, 1, -4, 1, 2, -1}, {6, 14, 32, 50, 82, 114}, 50] (* G. C. Greubel, Jun 23 2016 *)
  • PARI
    Vec(2*x^2*(3+x-x^2-2*x^3+x^5)/((1-x)^4*(1+x)^2) + O(x^100)) \\ Colin Barker, Jun 19 2016

Formula

From Colin Barker, Jun 19 2016: (Start)
a(n) = (6*(-9 + (-1)^n) + (25 + 3*(-1)^n)*n + 12*n^2 + 2*n^3)/12.
a(n) = (n^3 + 6*n^2 + 14*n - 24)/6 for n even.
a(n) = (n^3 + 6*n^2 + 11*n - 30)/6 for n odd.
a(n) = 2*a(n-1) + a(n-2) - 4*a(n-3) + a(n-4) + 2*a(n-5) - a(n-6) for n>7.
G.f.: 2*x^2*(3 + x - x^2 - 2*x^3 + x^5) / ((1-x)^4*(1+x)^2).
(End)

A058318 Number of energy levels in atoms of the n-th element of the periodic table.

Original entry on oeis.org

1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
Offset: 1

Views

Author

Labos Elemer, Dec 12 2000

Keywords

Comments

Run lengths, i.e., how many elements have 1,2,3,4,5,6,7 energy levels, are 2,8,8,18,18,32,26 (see A137583).

Examples

			For n=79, element 79 (Gold) has a(79)=6 energy levels (which may have 2,8,18,32,18,1 electrons).
		

Crossrefs

Programs

  • Maple
    seq(i$[2, 8, 8, 18, 18, 32, 32][i], i=1..7); # Michel Lagneau, Apr 03 2024

Formula

a(n) = m for s(m-1) < n <= s(m) for m=1..7, where s(m) = A173592(m) and s(0) = 0. - Michel Lagneau, Apr 03 2024

Extensions

a(106)-a(118) from Michel Lagneau, Apr 03 2024
Showing 1-3 of 3 results.