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A206589
Number of solutions (n,k) of p(k+1)=p(n+1) (mod n), where 1<=k<n.
2
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.
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
KEYWORD
nonn
AUTHOR
Clark Kimberling, Feb 09 2012
STATUS
approved