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A225566
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The set of magic numbers for an idealized harmonic oscillator atomic nucleus with a biaxially deformed prolate ellipsoid shape and an oscillator ratio of 3:1
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1
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2, 4, 6, 12, 18, 24, 36, 48, 60, 80, 100, 120, 150, 180, 210, 252, 294, 336, 392, 448, 504, 576, 648, 720, 810, 900, 990, 1100, 1210, 1320, 1452, 1584, 1716, 1872, 2028, 2184, 2366, 2548, 2730, 2940, 3150, 3360, 3600, 3840, 4080, 4352, 4624, 4896, 5202, 5508, 5814, 6156, 6498, 6840, 7220, 7600, 7980, 8400, 8820, 9240, 9702
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OFFSET
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1,1
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COMMENTS
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Partial sums of series of three doubled triangular numbers of the same value in order: 2,2,2,6,6,6,12,12,12,20,20,20... (cf. A002378).
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LINKS
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FORMULA
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a(n) = 2*a(n-1)-a(n-2)+2*a(n-3)-4*a(n-4)+2*a(n-5)-a(n-6)+2*a(n-7)-a(n-8) for n>8.
G.f.: 2*x / ((1-x)^4*(1+x+x^2)^2).
(End)
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MATHEMATICA
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Accumulate[Flatten[{#, #, #}&/@Accumulate[2*Range[30]]]] (* Harvey P. Dale, May 01 2014 *)
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PROG
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(PARI) Vec(2*x/((1-x)^4*(1+x+x^2)^2) + O(x^60)) \\ Colin Barker, Oct 01 2016
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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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