The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A139570 2n(n+3). 16
 0, 8, 20, 36, 56, 80, 108, 140, 176, 216, 260, 308, 360, 416, 476, 540, 608, 680, 756, 836, 920, 1008, 1100, 1196, 1296, 1400, 1508, 1620, 1736, 1856, 1980, 2108, 2240, 2376, 2516, 2660, 2808, 2960, 3116, 3276, 3440, 3608, 3780 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Numbers n such that 2*n+9 is a square. - Vincenzo Librandi, Nov 24 2010 a(n) appears also as the fourth member of the quartet [p0(n), p1(n), p2(n), a(n)] of the square of [n, n+1, n+2, n+3] in the Clifford algebra Cl_2 for n >= 0. p0(n) = -A147973(n+3), p1 = A046092(n) and p2(n) = A054000(n+1). See a comment on A147973, also with a reference. - Wolfdieter Lang, Oct 15 2014 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (3,-3,1). FORMULA a(n) = A028552(n)*2 = 2*n^2+6n = n(2n+6). a(n) = a(n-1)+4*n+4 (with a(0)=0). - Vincenzo Librandi, Nov 24 2010 a(n) = A022998(n) * A022998(n+3). - Paul Curtz, Mar 27 2011 a(n) = 4 * A000096(n). - Paul Curtz, Mar 27 2011 G.f.: 4*x*(2 - x)/(1 - x)^3. - Arkadiusz Wesolowski, Dec 31 2011 MATHEMATICA lst={}; Do[AppendTo[lst, 2*n*(n+3)], {n, 0, 6!}]; lst (* Vladimir Joseph Stephan Orlovsky, Nov 06 2008 *) Table[Sum[(2*i + n - 1), {i, 3, n}], {n, 2, 44}] (* Zerinvary Lajos, Jul 11 2009 *) CoefficientList[Series[4 x (2 - x)/(1 - x)^3, {x, 0, 40}], x] (* Vincenzo Librandi, May 23 2014 *) PROG (PARI) a(n)=2*n*(n+3) \\ Charles R Greathouse IV, Jun 17 2017 CROSSREFS Cf. A001105, A028552, A046092, A054000, A067728. Sequence in context: A348093 A186293 A158865 * A265207 A004118 A082231 Adjacent sequences: A139567 A139568 A139569 * A139571 A139572 A139573 KEYWORD easy,nonn AUTHOR Omar E. Pol, May 19 2008 STATUS approved

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

Last modified December 9 02:22 EST 2022. Contains 358698 sequences. (Running on oeis4.)