OFFSET

1,4

COMMENTS

Conjecture: a(n)>0 for all n>3. - Dmitry Kamenetsky, Feb 09 2017

LINKS

Zak Seidov, Table of n, a(n) for n = 1..1000

EXAMPLE

For n=5, p=11, there are a(5)=2 solutions from 11+5+1=17 and 11+7+1=19.

MATHEMATICA

Table[p = Prime[n]; c = 0; i = 1; While[i < n, If[PrimeQ[p + Prime[i] + 1], c = c + 1]; i++]; c, {n, 72}]

Table[p = Prime[n] + 1; Sum[If[PrimeQ[p + Prime[i]], 1, 0], {i, 1, n - 1}], {n, 72}] (* Zak Seidov, Apr 19 2013 *)

Table[Count[Prime[n]+Prime[Range[n-1]]+1, _?PrimeQ], {n, 80}] (* Harvey P. Dale, Mar 03 2024 *)

PROG

(PARI) for(n = 1, 72, q = prime (n) + 1; print1 (sum (i = 1, n - 1, isprime (q + prime (i))) ", "))\\ Zak Seidov, Apr 19 2013

CROSSREFS

KEYWORD

nonn

AUTHOR

Jayanta Basu, Apr 19 2013

STATUS

approved