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A167268
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Janet's sequence: Number of elements for each successively filled electronic subshell of an atom.
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14
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2, 2, 6, 2, 6, 2, 10, 6, 2, 10, 6, 2, 14, 10, 6, 2, 14, 10, 6, 2, 18, 14, 10, 6, 2, 18, 14, 10, 6, 2, 22, 18, 14, 10, 6, 2, 22, 18, 14, 10, 6, 2, 26, 22, 18, 14, 10, 6, 2, 26, 22, 18, 14, 10, 6, 2, 30, 26, 22, 18, 14, 10, 6, 2, 30, 26, 22, 18, 14, 10, 6
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OFFSET
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1,1
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COMMENTS
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The s-block is placed at
* the left, except row 1 (for Mendeleev-Moseley-Seaborg periodic table)
* the right (for Janet periodic table)
The number of elements in each block of Janet's periodic table are
s-block (1s to 8s): 8*2 = 16 elements;
p-block (2p to 7p): 6*6 = 36 elements;
d-block (3d to 6d): 4*10 = 40 elements;
f-block (4f to 5f): 2*14 = 28 elements.
The atomic numbers of elements in each block of Janet's periodic table are
s-block: 1,2, 3,4, 11,12, 19,20, 37,38, 55,56, 87,88, 119,120 (cf. A160914)
p-block: 5..10, 13..18, 31..36, 49..54, 81..86, 113..118 (cf. A138469)
d-block: 21..30, 39..48, 71..80, 103..112 (cf. A199934)
f-block: 57..70, 89..102 (cf. A217923).
The number of elements for each successive filled subshell are
s-block (1s): a(0)=2 terms (for H and He, i.e., 1 and 2);
s-block (2s): a(1)=2 terms (for Li and Be, i.e., 3 and 4);
p-block (2p): a(2)=6 terms (for B,C,N,O,F,Ne, i.e., 5 to 10);
s-block (3s): a(3)=2 terms (for Na,Mg, i.e., 11 and 12);
p-block (3p): a(4)=6 terms (for Al,Si,P,S,Cl,Ar, i.e., 13 to 18);
...
Reference, 2 leaflet 2, with Janet form (5). Extended.
Janet also envisaged an 'element zero' ('neutronium'?) - whose 'atom' would consist of two neutrons (and thus zero electrons, which would give a(0) = 0) and he speculated that this would be the link to a mirror-image table of elements with negative atomic numbers - in effect anti-matter (which would give a(-n) = -a(n), since positrons are negated electrons).
Maximum number of electrons for successive subshells of each shell of an atom, in the building up order (per aufbau principle and Madelung's rule).
Every term is twice an odd number since each filled subshell in block l has m going from -l to + l (2l+1 values,) each with 2 electrons (spin +1/2 and spin -1/2).
Blocks:
l=0: s (2 electrons) (first subshell of a shell, new period of Mendeleev's table)
l=1: p (6 electrons) (except for first shell, last subshell of a shell)
l=2: d (10 electrons)
l=3: f (14 electrons)
l=4: g (18 electrons)
...
l=l: ... (2*(2l+1) electrons)
The first subshell of the k-th shell has l = 0, k >= 1.
The second subshell of the k-th shell has l = floor(k/2), k >= 2.
The following subshells of the k-th shell have l decrementing down to 1, k >= 2.
(End)
Concatenation of finite arithmetic sequences, each followed by 2: { }, 2, { }, 2, {6}, 2, {6}, 2, {10, 6}, 2, {10, 6}, 2, {14, 10, 6}, 2, {14, 10, 6}, 2, {18, 14, 10, 6}, 2, {18, 14, 10, 6}, 2, ... - Daniel Forgues, May 15 2011
Named after the French mathematician Charles Janet (1849-1932). - Amiram Eldar, Jun 22 2021
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REFERENCES
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Charles Janet, Considérations sur la structure du noyau de l'atome, N 5, Décembre 1929, Beauvais, 2+45 pages, 4 leaflets.
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LINKS
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FORMULA
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MATHEMATICA
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row[n_] := Range[2, 4*Floor[n/2] + 2, 4]; Flatten[ Table[ row[n] // Reverse, {n, 0, 15}]] (* Jean-François Alcover, Oct 02 2012 *)
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PROG
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(Python)
from mpmath.libmp import sqrtrem
def a(n):
s, r = sqrtrem(n)
return 4 * (-n % (s + (r>s))) + 2
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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