login
a(n) = 190*n + 20.
5

%I #20 Apr 11 2024 17:22:13

%S 20,210,400,590,780,970,1160,1350,1540,1730,1920,2110,2300,2490,2680,

%T 2870,3060,3250,3440,3630,3820,4010,4200,4390,4580,4770,4960,5150,

%U 5340,5530,5720,5910,6100,6290,6480,6670,6860,7050,7240,7430

%N a(n) = 190*n + 20.

%C Numbers of the 20th column of positive numbers in the square array of nonnegative and polygonal numbers A139600. Also, numbers of the 20th column in the square array A057145.

%H Vincenzo Librandi, <a href="/A139620/b139620.txt">Table of n, a(n) for n = 0..5000</a>

%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1).

%F From _Elmo R. Oliveira_, Apr 08 2024: (Start)

%F G.f.: 10*(2+17*x)/(x-1)^2.

%F E.g.f.: 10*exp(x)*(2 + 19*x).

%F a(n) = 10*(A008601(n) + 2).

%F a(n) = 2*a(n-1) - a(n-2) for n >= 2. (End)

%t 190*Range[0,40]+20 (* or *) LinearRecurrence[{2,-1},{20,210},40] (* _Harvey P. Dale_, Feb 04 2019 *)

%o (Magma) [10*(19*n + 2): n in [0..50]]; // _Vincenzo Librandi_, Jul 23 2011

%o (PARI) a(n)=190*n+20 \\ _Charles R Greathouse IV_, Oct 05 2011

%Y Cf. A008601, A057145, A139600.

%K easy,nonn

%O 0,1

%A _Omar E. Pol_, May 21 2008