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A060820
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(2*n-1)^2 + (2*n)^2.
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3
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5, 25, 61, 113, 181, 265, 365, 481, 613, 761, 925, 1105, 1301, 1513, 1741, 1985, 2245, 2521, 2813, 3121, 3445, 3785, 4141, 4513, 4901, 5305, 5725, 6161, 6613, 7081, 7565, 8065, 8581, 9113, 9661, 10225, 10805, 11401, 12013, 12641, 13285, 13945, 14621, 15313
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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REFERENCES
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Marilyn vos Savant and Leonore Fleischer, Brain Building in Just 12 Weeks, Bantam Books, New York, NY, 1991, pp. 104-105, 119.
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LINKS
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FORMULA
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a(n) = 3*a(n-1)-3*a(n-2)+a(n-3). G.f.: x*(5+10*x+x^2)/(1-x)^3. - Colin Barker, Apr 22 2012
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EXAMPLE
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a(1)=5 because 1^2+2^2=5. a(2)=25 because 3^2+4^2=25.
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MATHEMATICA
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LinearRecurrence[{3, -3, 1}, {5, 25, 61}, 60] (* Harvey P. Dale, Oct 13 2020 *)
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PROG
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(PARI) for (n=1, 1000, write("b060820.txt", n, " ", (2*n - 1)^2 + (2*n)^2); ) \\ Harry J. Smith, Jul 12 2009
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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