A079115 Least k such that n+k is squarefree and coprime to n.

1, 1, 2, 1, 1, 1, 3, 3, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1, 1, 1, 3, 5, 1, 3, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 3, 3, 1, 1, 4, 5, 2, 1, 2, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 3, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 3, 2, 1, 1, 1, 3, 3, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1, 1, 1, 2, 1, 4, 3, 2, 1, 1, 1, 2, 1, 1

Offset

1,3

Comments

a(n) = A079114(n) - n.

Links

Antti Karttunen, Table of n, a(n) for n = 1..16384

Example

From Michael De Vlieger, Nov 23 2017: (Start)
First positions of values in a(n):
        n   a(n)
  --------------
        1     1
        3     2
        7     3
       47     4
       24     5
     1679     6
      120     7
      843     8
     2522     9
    72471    10
      840    11
    64050    13
  1674274    15
   404580    17
  2042040    19
(End)

Mathematica

Table[Block[{k = 1}, While[Nand[SquareFreeQ[n + k], CoprimeQ[n, n + k]], k++]; k], {n, 105}] (* Michael De Vlieger, Nov 23 2017 *)

Prog

(PARI) A079115(n) = { my(k=1); while((!issquarefree(n+k))||(gcd(n, n+k)>1), k++); k; } \\ Antti Karttunen, Nov 23 2017

Crossrefs

Cf. A005117, A079114.

Sequence in context: A238016 A185812 A152798 * A072906 A239062 A341052

Adjacent sequences: A079112 A079113 A079114 * A079116 A079117 A079118

Keyword

nonn

Author

Reinhard Zumkeller, Dec 25 2002

Status

approved