This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A157921 72n - 1. 2
 71, 143, 215, 287, 359, 431, 503, 575, 647, 719, 791, 863, 935, 1007, 1079, 1151, 1223, 1295, 1367, 1439, 1511, 1583, 1655, 1727, 1799, 1871, 1943, 2015, 2087, 2159, 2231, 2303, 2375, 2447, 2519, 2591, 2663, 2735, 2807, 2879, 2951, 3023, 3095, 3167, 3239 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The identity (72*n-1)^2-(36*n^2-n)*(12)^2=1 can be written as a(n)^2-A157286(n)*(12)^2=1. - Vincenzo Librandi, Jan 28 2012 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..10000 Vincenzo Librandi, X^2-AY^2=1 E. J. Barbeau, Polynomial Excursions, Chapter 10:Diophantine equations (2010), pages 84-85 (row 14 in the first table at p. 85, case d(t) = t*(6^2*t-1)). Index to sequences with linear recurrences with constant coefficients, signature (2,-1). FORMULA a(n) = 2*a(n-1)-a(n-2). - Vincenzo Librandi, Jan 28 2012 G.f.: x*(x+71)/(x-1)^2. - Vincenzo Librandi, Jan 28 2012 MATHEMATICA LinearRecurrence[{2, -1}, {71, 143}, 50] (* Vincenzo Librandi, Jan 28 2012 *) PROG (MAGMA) I:=[71, 143]; [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(72*n - 1", ")); \\ Vincenzo Librandi, Jan 28 2012 CROSSREFS Cf. A157286. Sequence in context: A111092 A140732 A025023 * A033224 A142178 A046004 Adjacent sequences:  A157918 A157919 A157920 * A157922 A157923 A157924 KEYWORD nonn,easy AUTHOR Vincenzo Librandi, Mar 09 2009 STATUS approved

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

Content is available under The OEIS End-User License Agreement .