A285454 Least number x such that x^n has n digits equal to k. Case k = 7.

7, 76, 83, 118, 206, 959, 1083, 726, 1387, 1114, 3313, 4011, 2184, 3881, 4792, 13071, 11564, 15523, 9208, 15232, 17771, 46336, 33815, 39147, 18083, 27624, 63435, 77276, 24354, 92341, 15776, 67006, 112877, 54468, 67996, 109996, 99376, 154083, 58937, 148722, 77335

Offset: 1

Author

Paolo P. Lava, Apr 19 2017

Keywords

• nonn
• base
• easy

Examples

			a(4) = 118 because 118^4 = 193877776 has 4 digits '7' and is the least number to have this property.
		

Links

• Martin Gossow, Table of n, a(n) for n = 1..100

Crossrefs

Cf. A039938.

Programs

Maple

P:=proc(q,h) local a,j,k,n,t; for n from 1 to q do for k from 1 to q do
a:=convert(k^n,base,10); t:=0; for j from 1 to nops(a) do if a[j]=h then t:=t+1; fi; od;
if t=n then print(k); break; fi; od; od; end: P(10^9,7);

Mathematica

f[n_] := Block[{k = 1}, While[ Count[ IntegerDigits[k^n], 7] != n, k++]; k]; Array[f, 41] (* Robert G. Wilson v, Apr 30 2017 *)