A068124 - OEIS

%I #16 Jul 12 2016 11:31:08

%S 1,15,322,1452,88909,2955639,25880899,415533397,215443469,

%T 25144122307797731891,1891851504074453542774,389309950637308214633931,

%U 71656315545775490294342978,8696027755149851609001142655

%N Smallest number whose n-th power begins with n n's; n-th root of A068123.

%C a(n) = A068123(n)^(1/n).

%H Ray Chandler, <a href="/A068124/b068124.txt">Table of n, a(n) for n = 1..22</a>

%e a(3) = 322 as 322^3 = 33386248 begins with 333.

%t a[n_] := Block[{t = Flatten@Table[IntegerDigits@n, {n}], m, v, h=0}, m = Length@t; z = FromDigits@t; While[ Take[ IntegerDigits[(v = Ceiling[(z 10^h) ^ (1/n)])^n], m] != t, h++]; v]; Array[a, 30] (* _Giovanni Resta_, Jul 12 2016 *)

%Y Cf. A068123.

%K base,easy,nonn

%O 1,2

%A _Amarnath Murthy_, Feb 21 2002

%E Corrected and extended by _David Wasserman_, Dec 23 2002

%E More terms from _Sascha Kurz_, Feb 09 2003

%E Entry revised by _N. J. A. Sloane_, Aug 14 2006