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A114619
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a(n) = 2*A079291(n) (twice squares of Pell numbers).
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2
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0, 2, 8, 50, 288, 1682, 9800, 57122, 332928, 1940450, 11309768, 65918162, 384199200, 2239277042, 13051463048, 76069501250, 443365544448, 2584123765442, 15061377048200, 87784138523762, 511643454094368
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OFFSET
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0,2
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LINKS
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FORMULA
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G.f.: 2*x*(1-x)/((1+x)*(1-6*x+x^2)).
a(n) = A001333(n)^2 - (-1)^n. - Antonio Pane (apane1(AT)spc.edu), Dec 15 2007
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MATHEMATICA
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PROG
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(Magma) [n le 3 select 2*(n-1)^2 else 5*Self(n-1) +5*Self(n-2) -Self(n-3): n in [1..31]]; // G. C. Greubel, Aug 18 2022
(SageMath) [2*lucas_number1(n, 2, -1)^2 for n in (0..30)] # G. C. Greubel, Aug 18 2022
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CROSSREFS
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KEYWORD
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easy,nonn,changed
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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