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A053741
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Sum of even numbers in range 10*n to 10*n+9.
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3
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20, 70, 120, 170, 220, 270, 320, 370, 420, 470, 520, 570, 620, 670, 720, 770, 820, 870, 920, 970, 1020, 1070, 1120, 1170, 1220, 1270, 1320, 1370, 1420, 1470, 1520, 1570, 1620, 1670, 1720, 1770, 1820, 1870, 1920, 1970, 2020, 2070, 2120, 2170, 2220, 2270
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OFFSET
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0,1
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LINKS
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FORMULA
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a(n) = 50*n + 20.
a(n) = 2*a(n-1) - a(n-2).
G.f.: 10*(2+3*x)/(1-x)^2. (End)
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EXAMPLE
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20 is sum of 0, 2, 4, 6, 8;
70 is sum of 10, 12, 14, 16, 18;
120 is sum of 20, 22, 24, 26, 28; etc.
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MAPLE
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MATHEMATICA
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PROG
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(Sage) [10*(2+5*n) for n in (0..50)] # G. C. Greubel, Sep 06 2019
(GAP) List([0..50], n-> 10*(2+5*n)); # G. C. Greubel, Sep 06 2019
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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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