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)
MAPLE
seq(18*n+1, n=0..60); # G. C. Greubel, Sep 18 2019
MATHEMATICA
Range[1, 1000, 18] (* Vladimir Joseph Stephan Orlovsky, Jun 01 2011 *)
LinearRecurrence[{2, -1}, {1, 19}, 60] (* G. C. Greubel, Feb 17 2017 *)
PROG
(PARI) vector(60, n, 18*n-17) \\ G. C. Greubel, Feb 17 2017
(Magma) [18*n +1: n in [0..60]]; // G. C. Greubel, Sep 18 2019
(Sage) [18*n+1 for n in (0..60)] # G. C. Greubel, Sep 18 2019
(GAP) List([0..60], n-> 18*n+1); # G. C. Greubel, Sep 18 2019
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Reinhard Zumkeller, Jun 17 2009
STATUS
approved