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A093907
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Number of elements in the n-th period of the periodic table.
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17
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2, 8, 8, 18, 18, 32, 32, 50, 50, 72, 72, 98, 98, 128, 128, 162, 162, 200, 200, 242, 242, 288, 288, 338, 338, 392, 392, 450, 450, 512, 512, 578, 578, 648, 648, 722, 722, 800, 800, 882, 882, 968, 968, 1058, 1058, 1152, 1152, 1250, 1250, 1352, 1352, 1458, 1458
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OFFSET
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1,1
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COMMENTS
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Maximum number of electrons in the n-th shell of an atom. - Daniel Forgues, May 9, 2011
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REFERENCES
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Restrepo, G. and Pachon, L., Pythagoras and the Periodic Table, Journal of Chemical Education, submitted, 2004.
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LINKS
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Harry J. Smith, Table of n, a(n) for n=1,...,20000
M. Winter, WebElements Periodic Table
Journal of Chemical Education
OEIS Wiki, Bohr's aufbau principle
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FORMULA
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a(n)=2*floor((n+2)/2)^2. - Leonardo Pachon (leaupaco(AT)yahoo.es), Jul 31 2004
a(n) = 2*A008794(n+2). G.f.: 2*x*(1+3*x-x^3-2*x^2+x^4)/((1+x)^2*(1-x)^3 ). [From R. J. Mathar, Oct 04 2009]
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EXAMPLE
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a(1) = 2: H and He.
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PROG
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(PARI) { for (n=1, 20000, a=2*floor((n+2)/2)^2; write("b093907.txt", n, " ", a); ) } [From Harry J. Smith, Jun 17 2009]
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CROSSREFS
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Cf. A116471.
Sequence in context: A104537 A019240 * A116471 A146749 A180825 A064231
Adjacent sequences: A093904 A093905 A093906 * A093908 A093909 A093910
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KEYWORD
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nonn
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AUTHOR
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Guillermo Restrepo, May 26 2004
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EXTENSIONS
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Added more terms. Harry J. Smith, Jun 17 2009
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STATUS
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approved
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