

A289690


Least k such that there are exactly n perfect powers between 10k and 10k + 10.


0




OFFSET

0,1


COMMENTS

I do not know if a(5) exists. If it does, the numbers 10k+1, 10k+3, 10k+5, 10k+7, 10k+9 will be perfect powers. But those numbers are very scarce.
Further, a(6), ..., a(10) cannot exist because of the Mihailescu theorem, as the only adjoining perfect powers are 8 and 9.


LINKS



EXAMPLE

If n=2, then there are 2 power numbers between 20 and 30: 25 and 27, and this is the least k with this property.


PROG

(PARI) a(n)=my(k=0); while(sum(j=10*k+1, 10*k+9, (j==1)  ispower(j)) !=n, k++); k; \\ Michel Marcus, Jul 20 2017


CROSSREFS



KEYWORD

nonn,fini


AUTHOR



STATUS

approved



