This site is supported by donations to The OEIS Foundation.

 Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS". Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A000472 a(n) = a(n-1)^2 + (a(n-2) + 1)(a(n-1) - a(n-2)^2 ). 1
 2, 5, 28, 802, 643726, 414383582242, 171713753231982206218246, 29485613049014079571725771288849499850026859242 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 REFERENCES Damiani, E.; D'Antona, O.; Naldi, G.; and Pavarino, L.; Tiling bricks with bricks. Stud. Appl. Math. 83 (1990), number 2, 91-110. LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..14 MAPLE 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; MATHEMATICA 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 *) PROG (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 CROSSREFS Sequence in context: A292499 A105787 A110497 * A248235 A049050 A178322 Adjacent sequences:  A000469 A000470 A000471 * A000473 A000474 A000475 KEYWORD nonn,nice,easy AUTHOR Ottavio D'Antona [ dantona(AT)hermes.dsi.unimi.it ] STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.