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 A176662 a(0)=2, a(1)=7, and a(n) = (3*n+1)*2^(n-1) if n > 1. 2
 2, 7, 14, 40, 104, 256, 608, 1408, 3200, 7168, 15872, 34816, 75776, 163840, 352256, 753664, 1605632, 3407872, 7208960, 15204352, 31981568, 67108864, 140509184, 293601280, 612368384, 1275068416, 2650800128, 5502926848, 11408506880, 23622320128, 48855252992 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS The sequence appears on the main diagonal of the array defined by A123167 in the first row and successive differences in followup rows: 2, 3, 10, 7, 18, 11, 26, 15, 34, 19, ... A123167 1, 7, -3, 11, -7, 15, -11, 19, -15, 23, ... first diff 6, -10, 14, -18, 22 -26, 30, -34, 38, ... second diff -16, 24, -32, 40, -48, 56, -64, 72, -80, ... third diff LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (4,-4). FORMULA a(n) mod 9 = A010710(n-1), n > 2. a(2n) + a(2n+1) = 9, 54, 360, 2016, ... a(n) - 2*a(n-1) = 12*A131577(n-2), n > 1. a(n) = 4*a(n-1) - 4*a(n-2), n > 3. G.f.: (-6*x^2+12*x^3+2-x)/(1-2*x)^2. MATHEMATICA LinearRecurrence[{4, -4}, {2, 7, 14, 40}, 40] (* or *) Join[{2, 7}, Table[ (3n+1) 2^(n-1), {n, 2, 40}]] (* Harvey P. Dale, Oct 05 2019 *) CROSSREFS Sequence in context: A194590 A107373 A336579 * A018526 A329115 A018542 Adjacent sequences:  A176659 A176660 A176661 * A176663 A176664 A176665 KEYWORD nonn,easy AUTHOR Paul Curtz, Apr 23 2010 EXTENSIONS Edited by R. J. Mathar, Jun 30 2010 STATUS approved

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Last modified September 30 18:12 EDT 2020. Contains 337440 sequences. (Running on oeis4.)