A071702 Number of twin prime pairs <= n of form (4*k+3,4*(k+1)+1), k>=0.

0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4

Offset: 1

Author

Reinhard Zumkeller, Jun 04 2002

Keywords

• nonn

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 (aHarvey P. Dale, Nov 12 2021

Examples

			a(60)=3, since (59,61) is included along with (3,5) and (11,13).
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

a(n) = A071538(n) - A071701(n), cf. A071698, A071699.

Programs

Mathematica

Accumulate[Table[If[AllTrue[{n,n+2},PrimeQ]&&Mod[n,4]==3,1,0],{n,100}]] (* Harvey P. Dale, Nov 12 2021 *)