OFFSET
1,4
COMMENTS
a(n)=0 iff n is squarefree; otherwise a(n) > 1.
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..16384
EXAMPLE
The nearest squarefree numbers surrounding 25 = 5^2 are A070321(25) = 23 and A067535(25) = 26, therefore a(25) = 26-23 = 3. - Edited by Antti Karttunen, Nov 23 2017
MATHEMATICA
Block[{nn = 105, s}, s = Select[Range[nn + 15], SquareFreeQ]; Array[If[FreeQ[s, #], First@ Differences@ s[[# - 1 ;; #]] &@ FirstPosition[Union@ Append[s, #], #][[1]], 0] &, 105]] (* Michael De Vlieger, Nov 23 2017 *)
PROG
(PARI)
A067535(n) = { while(!issquarefree(n), n++); n; } \\ These two functions from Michel Marcus, Mar 18 2017
A070321(n) = { while(!issquarefree(n), n--); n; }
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Oct 03 2002
EXTENSIONS
Definition corrected to match with the data as the old definition was that of A080733 - Antti Karttunen, Nov 23 2017
STATUS
approved