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A000472
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a(n) = a(n-1)^2 + (a(n-2) + 1)*(a(n-1) - a(n-2)^2).
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1
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OFFSET
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1,1
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REFERENCES
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Damiani, E.; D'Antona, O.; Naldi, G.; and Pavarino, L.; Tiling bricks with bricks. Stud. Appl. Math. 83 (1990), number 2, 91-110.
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 1..14
Index entries for sequences related to bricks
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MAPLE
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A000472 := proc(n) option remember; if n<=2 then 3*n-1 else A000472(n-1)^2+(1+A000472(n-2))*(A000472(n-1)-A000472(n-2)^2); fi; end;
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MATHEMATICA
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RecurrenceTable[{a[1]==2, a[2]==5, a[n]==a[n-1]^2+(a[n-2]+1)(a[n-1]- a[n-2]^2)}, a[n], {n, 10}] (* Harvey P. Dale, Sep 29 2011 *)
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PROG
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(Magma) I:=[2, 5]; [n le 2 select I[n] else Self(n-1)^2 + (Self(n-2)+1)*(Self(n-1)-Self(n-2)^2 ): n in [1..10]]; // Vincenzo Librandi, Sep 30 2011
(Haskell)
a000472 n = a000472_list !! (n-1)
a000472_list = 2 : 5 : zipWith (+) (map (^ 2) $ tail a000472_list)
(zipWith (*) (map (+ 1) a000472_list)
(zipWith (-) (tail a000472_list)
(map (^ 2) a000472_list)))
-- Reinhard Zumkeller, Oct 03 2012
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CROSSREFS
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Sequence in context: A306893 A105787 A110497 * A248235 A358444 A327345
Adjacent sequences: A000469 A000470 A000471 * A000473 A000474 A000475
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KEYWORD
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nonn,nice,easy
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AUTHOR
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Ottavio D'Antona [ dantona(AT)hermes.dsi.unimi.it ]
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STATUS
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approved
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