OFFSET
1,5
COMMENTS
Conjecture: a(n)>0 for all n>2. - Dmitry Kamenetsky, Feb 09 2017
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..10000
MAPLE
a:= n-> add(`if`(isprime(ithprime(n)+ithprime(i)-1), 1, 0), i=1..n-1):
seq(a(n), n=1..100); # Alois P. Heinz, Apr 18 2013
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[Count[Prime[n]+Prime[Range[n-1]]-1, _?PrimeQ], {n, 80}] (* Harvey P. Dale, Nov 04 2020 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Jayanta Basu, Apr 17 2013
STATUS
approved