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 A161705 a(n) = 18*n + 1. 18
 1, 19, 37, 55, 73, 91, 109, 127, 145, 163, 181, 199, 217, 235, 253, 271, 289, 307, 325, 343, 361, 379, 397, 415, 433, 451, 469, 487, 505, 523, 541, 559, 577, 595, 613, 631, 649, 667, 685, 703, 721, 739, 757, 775, 793, 811, 829, 847, 865, 883, 901, 919, 937, 955 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Digital root of a(n) is 1. - Alexander R. Povolotsky, Jun 13 2012 These numbers can be written as the sum of four integer cubes as a(n) = (2*n + 14)^3 + (3*n + 30)^3 + (- 2*n - 23)^3 + (- 3*n - 26)^3. - Arkadiusz Wesolowski, Aug 15 2013 LINKS G. C. Greubel, Table of n, a(n) for n = 0..2500 Index entries for linear recurrences with constant coefficients, signature (2,-1). FORMULA a(n) = 18*n + 1, n >= 0. a(n) = a(n-1) + 18 (with a(0)=1). - Vincenzo Librandi, Dec 27 2010 From G. C. Greubel, Feb 17 2017: (Start) G.f.: (1 + 17*x)/(1-x)^2. E.g.f.: (1 + 18*x)*exp(x). a(n) = 2*a(n-1) - a(n-2). (End) MATHEMATICA Range[1, 1000, 18] (* Vladimir Joseph Stephan Orlovsky, Jun 01 2011 *) LinearRecurrence[{2, -1}, {1, 19}, 50] (* G. C. Greubel, Feb 17 2017 *) PROG (PARI) for(n=0, 25, print1(18*n+1, ", ")) \\ G. C. Greubel, Feb 17 2017 CROSSREFS Cf. A161700, A005408, A016813, A016921, A017281, A017533, A158057, A161709, A161714, A128470, A287326 (fourth column). Sequence in context: A245363 A109639 A225863 * A131600 A175546 A162471 Adjacent sequences:  A161702 A161703 A161704 * A161706 A161707 A161708 KEYWORD nonn,easy AUTHOR Reinhard Zumkeller, Jun 17 2009 STATUS approved

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Last modified December 10 20:55 EST 2018. Contains 318049 sequences. (Running on oeis4.)