A257116 -id:A257116 - cp's OEIS frontend

Showing 1-1 of 1 results.

A257115 Smallest k such that none of k + 1, k + 3,... k + 2n - 1 are squarefree and all of k + 2, k + 4,... k + 2n are squarefree.

Original entry on oeis.org

1, 3, 15, 15, 49, 483, 5049, 6347, 144945

Offset: 0

Juri-Stepan Gerasimov, Apr 25 2015

For any x, one of x+2, x+4, ..., x+18 is divisible by 9 and thus not squarefree, so a(n) does not exist for n >= 9. - Robert Israel, Apr 27 2015

			a(0) = 1 because 1 + 0 = 1 is squarefree.
a(1) = 3 because 3 + 1 = 4 is not squarefree and 3 + 2 = 5 is squarefree.

Cf. A257108, A257116.

a(n)=k=1;while(k,c=0;for(i=1,n,if(!issquarefree(k+2*i-1)&&issquarefree(k+2*i),c++);if(issquarefree(k+2*i-1)||!issquarefree(k+2*i),c=0;break));if(c==n,return(k));k++)
vector(9,n,n--;a(n)) \\ Derek Orr, Apr 27 2015

Corrected and extended by Derek Orr, Apr 27 2015

Showing 1-1 of 1 results.