OFFSET
1,11
COMMENTS
As for A071538 the convention is followed that a twin prime pair is <= n if its smaller member is <= n.
If {a,b} is a twin prime pair (a<b), and Mod[a,4]==3, there is no need to test b because it must be 1 Mod 4. - Harvey P. Dale, Nov 12 2021
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
EXAMPLE
a(60)=3, since (59,61) is included along with (3,5) and (11,13).
MATHEMATICA
Accumulate[Table[If[AllTrue[{n, n+2}, PrimeQ]&&Mod[n, 4]==3, 1, 0], {n, 100}]] (* Harvey P. Dale, Nov 12 2021 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Jun 04 2002
STATUS
approved