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A157287 a(n) = 1728*n - 24. 3
1704, 3432, 5160, 6888, 8616, 10344, 12072, 13800, 15528, 17256, 18984, 20712, 22440, 24168, 25896, 27624, 29352, 31080, 32808, 34536, 36264, 37992, 39720, 41448, 43176, 44904, 46632, 48360, 50088, 51816, 53544, 55272, 57000, 58728 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
The identity (10368*n^2 - 288*n + 1)^2 - (36*n^2-n)*(1728*n-24)^2 = 1 can be written as A157288(n)^2 - A157286(n)*a(n)^2 = 1 (see also second part of the initial comment in A157286). - Vincenzo Librandi, Jan 28 2012
LINKS
Vincenzo Librandi, X^2-AY^2=1
FORMULA
a(n) = 2*a(n-1) - a(n-2). - Vincenzo Librandi, Jan 28 2012
G.f.: x*(24*x+1704)/(x-1)^2. - Vincenzo Librandi, Jan 28 2012
MATHEMATICA
LinearRecurrence[{2, -1}, {1704, 3432}, 40] (* Vincenzo Librandi, Jan 28 2012 *)
PROG
(Magma) I:=[1704, 3432]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..50]]; // Vincenzo Librandi, Jan 28 2012
(PARI) for(n=1, 40, print1(1728*n-24", ")); \\ Vincenzo Librandi, Jan 28 2012
CROSSREFS
Sequence in context: A210121 A345506 A345782 * A029559 A222553 A345516
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Feb 27 2009
EXTENSIONS
Comment rewritten by Bruno Berselli, Jan 28 2012
STATUS
approved

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Last modified May 23 05:11 EDT 2024. Contains 372758 sequences. (Running on oeis4.)