OFFSET
0,1
COMMENTS
a(n) = 0 for n = 20, 165, 467, ... . Do there exist infinitely many such values of n?
These values of 0 are all conjectural. - Robert Israel, Apr 28 2021
EXAMPLE
a(1) = 5 since 5 is the least prime that generates exactly one prime 7=5+3-1 of the given form. Again a(3) = 13 since 13 generates exactly 3 primes 17=13+5-1, 19=13+7-1 and 23=13+11-1 of the given form.
MATHEMATICA
Cn[n_] := Module[{c}, p = Prime[n]; c = 0; i = 1; While[i < n, If[PrimeQ[p + Prime[i] - 1], c = c + 1] i++]; c]; t = {};
Do[p = 0; j = 0; While[++j < 2000 && p != 1, If[Cn[j] == k, AppendTo[t, Prime[j]]; p = 1, p = 0]]; If[p == 0, AppendTo[t, 0]], {k, 0, 200}]; t
CROSSREFS
KEYWORD
nonn
AUTHOR
Jayanta Basu, Apr 18 2013
EXTENSIONS
Definition clarified by Robert Israel, Apr 28 2021
STATUS
approved