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A007449
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a(0) = 7, a(1) = 9; for n >= 0, a(2n+1) = a(2n-1)^2 - a(2n-2), a(2n+2) = a(2n)^2 - a(2n+1).
(Formerly M4337)
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0
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7, 9, 40, 74, 1526, 5436, 2323240, 29548570, 5397414549030, 873117986721660, 29132083813207600287219240, 762335018736884842676898606570, 848678307299752276902028307632840866100214927571030
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OFFSET
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0,1
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REFERENCES
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Intelligence test in Chess Life, Vol. 49(#6) 1994, p. 14.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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Table of n, a(n) for n=0..12.
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FORMULA
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a(n+1) = a(n-1)^2 - a(n - 2*(1 - n mod 2)), a(0)=7, a(1)=9. - Reinhard Zumkeller, Mar 25 2003
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PROG
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(PARI) a(n)=if(n<0, 0, if(n<2, [7, 9][n+1], a(n-2)^2-a(n-2+(-1)^n)))
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CROSSREFS
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Sequence in context: A057590 A140787 A032695 * A189053 A067649 A025631
Adjacent sequences: A007446 A007447 A007448 * A007450 A007451 A007452
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane.
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EXTENSIONS
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More terms from Reinhard Zumkeller, Mar 25 2003
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STATUS
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approved
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