A013895 - OEIS

%I #17 Sep 08 2022 08:44:38

%S 400,1280000000,4096000000000000,13107200000000000000000,

%T 41943040000000000000000000000,134217728000000000000000000000000000,

%U 429496729600000000000000000000000000000000,1374389534720000000000000000000000000000000000000

%N a(n) = 20^(5*n+2).

%H Vincenzo Librandi, <a href="/A013895/b013895.txt">Table of n, a(n) for n = 0..50</a>

%H Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a>

%H <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (3200000).

%F a(n) = 3200000*a(n-1), a(0)=400. - _Vincenzo Librandi_, May 27 2011

%F G.f.: -400 / (3200000*x-1). - _Colin Barker_, Nov 17 2015

%F a(n) = A009964(A016873(n)). - _Wesley Ivan Hurt_, Nov 17 2015

%p A013895:=n->20^(5*n+2): seq(A013895(n), n=0..10); # _Wesley Ivan Hurt_, Nov 17 2015

%t 20^(5 Range[0, 10] + 2) (* or *) CoefficientList[Series[-400/(3200000*x - 1), {x, 0, 10}], x] (* _Wesley Ivan Hurt_, Nov 17 2015 *)

%o (Magma) [20^(5*n+2): n in [0..10]]; // _Vincenzo Librandi_, May 27 2011

%o (PARI) Vec(-400/(3200000*x-1) + O(x^10)) \\ _Colin Barker_, Nov 17 2015

%Y Cf. A009964, A016873.

%K nonn,easy

%O 0,1

%A _N. J. A. Sloane_