A285449 Least number x such that x^n has n digits equal to k. Case k = 2.

2, 15, 138, 255, 186, 289, 418, 2619, 1846, 1532, 2551, 3142, 3235, 10567, 5755, 14083, 10481, 10399, 18565, 11703, 33933, 17668, 36766, 38724, 37841, 35933, 67309, 83236, 69451, 57508, 107027, 52016, 38672, 118132, 138785, 84636, 112234, 131131, 138087, 152719

Offset

1,1

Links

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

Example

a(4) = 255 because 255^4 = 4228250625 has 4 digits '2' and is the least number to have this property.

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, 2);

Mathematica

Table[x = 1; While[DigitCount[x^n, 10, 2] != n, x++]; x, {n, 40}] (* Michael De Vlieger, Apr 25 2017 *)

Prog

(PARI) A285449vec=(n, {k=2})->{my(L:list, c); L=List(); for(t=1, n, forstep(y=1, +oo, 1, c=digits(y^t); if(sum(j=1, #c, c[j]==k)==t, listput(L, y); break()))); return(Vec(L))} \\ R. J. Cano, Apr 29 2017

Crossrefs

Sequence in context: A214043 A347993 A215922 * A371584 A288950 A005415

Adjacent sequences: A285446 A285447 A285448 * A285450 A285451 A285452

Keyword

nonn,base

Author

Paolo P. Lava, Apr 19 2017

Status

approved