cp's OEIS Frontend

A266959 Smallest n-digit number ending in n.

%I A266959 #30 Sep 08 2022 08:46:15
%S A266959 1,12,103,1004,10005,100006,1000007,10000008,100000009,1000000010,
%T A266959 10000000011,100000000012,1000000000013,10000000000014,
%U A266959 100000000000015,1000000000000016,10000000000000017,100000000000000018,1000000000000000019,10000000000000000020
%N A266959 Smallest n-digit number ending in n.
%C A266959 Digital sum of a(n) = digsum(n) + 1 for n>1.
%C A266959 3, 229, 4987 are the initial values of n for prime a(n). - _Altug Alkan_, Jan 17 2016
%H A266959 Colin Barker, <a href="/A266959/b266959.txt">Table of n, a(n) for n = 1..1000</a>
%H A266959 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (12,-21,10).
%F A266959 a(n) = n + 10^(n-1) for n>1 with a(1) = 1.
%F A266959 a(n) = A081552(n) - 1 for n>1. - _Michel Marcus_, Jan 10 2016
%F A266959 From _Colin Barker_, Jan 10 2016: (Start)
%F A266959 a(n) = 12*a(n-1) - 21*a(n-2) + 10*a(n-3) for n>3.
%F A266959 G.f.: x*(1-20*x^2+10*x^3) / ((1-x)^2*(1-10*x)). (End)
%e A266959 a(4) = 1004 because it is the smallest 4-digit number ending in 4.
%p A266959 A266959:=n->n+10^(n-1): 1, seq(A266959(n), n=2..30);
%t A266959 Join[{1}, Table[n + 10^(n - 1), {n, 2, 20}]]
%o A266959 (Magma) [1] cat [n+10^(n-1): n in [2..30]]; // _Vincenzo Librandi_, Jan 10 2016
%o A266959 (PARI) Vec(x*(1-20*x^2+10*x^3)/((1-x)^2*(1-10*x)) + O(x^30)) \\ _Colin Barker_, Jan 10 2016
%o A266959 (PARI) a(n) = if(n==1, 1, n + 10^(n-1)); \\ _Altug Alkan_, Jan 17 2016
%o A266959 (Python)
%o A266959 def A266959(n): return n+10**(n-1) if n > 1 else 1 # _Chai Wah Wu_, Jul 25 2022
%Y A266959 Cf. A007953 (digsum), A081552, A279913.
%K A266959 nonn,easy,base
%O A266959 1,2
%A A266959 _Wesley Ivan Hurt_, Jan 09 2016