A206589 Number of solutions (n,k) of p(k+1)=p(n+1) (mod n), where 1<=k<n.

1, 0, 2, 1, 2, 1, 1, 1, 1, 0, 3, 1, 2, 1, 2, 0, 2, 0, 2, 1, 2, 1, 1, 0, 0, 1, 1, 0, 4, 1, 2, 2, 2, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 2, 1, 0, 3, 1, 1, 1, 1, 0, 2, 1, 2, 2, 1, 1, 4, 0, 1, 1, 0, 0, 2, 0, 2, 2, 3, 0, 4, 1, 2, 2, 1, 1, 3, 1, 2, 1, 2, 1, 3, 1, 3, 2, 3, 1, 3, 0, 1, 0, 2, 1, 2, 0, 2, 0, 2

Offset

2,3

Comments

Related to A206588, which includes differences p-2.

Links

Table of n, a(n) for n=2..100.

Example

For k=1 to 5, the numbers p(7)-p(k+1) are 14,12,10,6,4, so that a(6)=2.

Mathematica

f[n_, k_]:=If[Mod[Prime[n+1]-Prime[k+1], n]==0, 1, 0];
t[n_] := Flatten[Table[f[n, k], {k, 1, n - 1}]]
a[n_] := Count[Flatten[t[n]], 1]
Table[a[n], {n, 2, 120}]  (* A206589 *)

Crossrefs

Cf. A206588.

Sequence in context: A172303 A064391 A236470 * A086011 A124760 A077619

Adjacent sequences: A206586 A206587 A206588 * A206590 A206591 A206592

Keyword

nonn

Author

Clark Kimberling, Feb 09 2012

Status

approved