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A107585 a(n) = 5^n - 5*n. 10

%I

%S 1,0,15,110,605,3100,15595,78090,390585,1953080,9765575,48828070,

%T 244140565,1220703060,6103515555,30517578050,152587890545,

%U 762939453040,3814697265535,19073486328030,95367431640525,476837158203020,2384185791015515,11920928955078010,59604644775390505,298023223876953000

%N a(n) = 5^n - 5*n.

%C Numbers a(n)=k such that the number m with n 5's and k 1's has digit product = digit sum = 5^n.

%H Vincenzo Librandi, <a href="/A107585/b107585.txt">Table of n, a(n) for n = 0..1000</a>

%H <a href="/index/Rec&#34;order_03">Index entries for linear recurrences with constant coefficients</a>, signature (7,-11,5)

%F a(n) = 7*a(n-1) - 11*a(n-2) + 5*a(n-3), n >= 3. - _Vincenzo Librandi_, Oct 26 2011

%F G.f.: ( -1-26*x^2+7*x ) / ( (5*x-1)*(x-1)^2 ). - _R. J. Mathar_, Oct 26 2011

%e Corresponding numbers m are 1, 5, 11111111111111155, ...

%t Table[5^m-5*m, {m, 0, 10}]

%t LinearRecurrence[{7,-11,5},{1,0,15},30] (* _Harvey P. Dale_, Oct 21 2015 *)

%o (MAGMA) [(5^n - 5*n): n in [0..25]]; // _Vincenzo Librandi_, Dec 16 2010

%o (PARI) a(n)=5^n-5*n \\ _Charles R Greathouse IV_, Oct 26 2011

%Y Cf. A107583, A107584.

%K nonn,easy

%O 0,3

%A _Zak Seidov_, May 16 2005

%E Corrected by _Charles R Greathouse IV_, Sep 08 2012

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Last modified November 22 02:58 EST 2019. Contains 329383 sequences. (Running on oeis4.)