A086943 Integers k such that R(k+7) = 3.
23, 293, 2993, 29993, 299993, 2999993, 29999993, 299999993, 2999999993, 29999999993, 299999999993, 2999999999993, 29999999999993, 299999999999993, 2999999999999993, 29999999999999993, 299999999999999993, 2999999999999999993, 29999999999999999993, 299999999999999999993
Offset: 1
Links
- Vincenzo Librandi, Table of n, a(n) for n = 1..300
- Index entries for linear recurrences with constant coefficients, signature (11,-10).
Programs
-
Magma
[3*10^n-7: n in [1..25] ]; // Vincenzo Librandi, Aug 22 2011
-
Mathematica
FromDigits/@Table[Join[{2},Table[9,{n}],{3}],{n,0,20}] (* Harvey P. Dale, Aug 21 2011 *) Table[ 10*FromDigits[PadRight[{2},n,9]]+3,{n,20}] (* Harvey P. Dale, Aug 05 2025 *) -
Maxima
A086943(n):=3*10^n-7$ makelist(A086943(n),n,1,17); /* Martin Ettl, Nov 08 2012 */
Formula
a(n) = 3*10^n - 7.
R(a(n)) = A086942(n).
From Elmo R. Oliveira, Apr 30 2025: (Start)
G.f.: x*(40*x+23)/((x-1)*(10*x-1)).
E.g.f.: 4 - 7*exp(x) + 3*exp(10*x).
a(n) = 11*a(n-1) - 10*a(n-2) for n > 2. (End)