login
a(n) = (41^n - 1)/40.
6

%I #20 Aug 27 2024 21:47:23

%S 0,1,42,1723,70644,2896405,118752606,4868856847,199623130728,

%T 8184548359849,335566482753810,13758225792906211,564087257509154652,

%U 23127577557875340733,948230679872888970054,38877457874788447772215,1593975772866326358660816,65353006687519380705093457

%N a(n) = (41^n - 1)/40.

%C Partial sums of powers of 41 (A009985).

%H Vincenzo Librandi, <a href="/A218744/b218744.txt">Table of n, a(n) for n = 0..600</a>

%H <a href="/index/Par#partial">Index entries related to partial sums</a>.

%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (42,-41).

%F a(n) = floor(41^n/40).

%F G.f.: x/((1-x)*(1-41*x)). - _Vincenzo Librandi_, Nov 07 2012

%F a(n) = 42*a(n-1) - 41*a(n-2). - _Vincenzo Librandi_, Nov 07 2012

%F E.g.f.: exp(21*x)*sinh(20*x)/20. - _Elmo R. Oliveira_, Aug 27 2024

%t LinearRecurrence[{42, -41}, {0, 1}, 30] (* _Vincenzo Librandi_, Nov 07 2012 *)

%o (PARI) A218744(n)=41^n\40

%o (Magma) [n le 2 select n-1 else 42*Self(n-1)-41*Self(n-2): n in [1..20]]; // _Vincenzo Librandi_, Nov 07 2012

%o (Maxima) A218744(n):=(41^n-1)/40$

%o makelist(A218744(n),n,0,30); /* _Martin Ettl_, Nov 07 2012 */

%Y Cf. similar sequences of the form (k^n-1)/(k-1): A000225, A003462, A002450, A003463, A003464, A023000, A023001, A002452, A002275, A016123, A016125, A091030, A135519, A135518, A131865, A091045, A218721, A218722, A064108, A218724-A218734, A132469, A218736-A218753, A133853, A094028, A218723.

%Y Cf. A009985.

%K nonn,easy

%O 0,3

%A _M. F. Hasler_, Nov 04 2012