A093708 Number of odd nonprime differences of 2 (twin odd nonprimes) below 10^n.

0, 9, 200, 2748, 32041, 351174, 3729823, 38917403, 401729439, 4117307658, 41988266423, 426654761185, 4323703591195, 43725896820062, 441488068396967, 4451827513629449, 44843834524044694, 451328767313095717

Offset: 1

Author

Enoch Haga, Apr 10 2004

Keywords

• nonn
• more

Comments

Count twin odd nonprimes below 10^n.

Examples

			a(2) = 9 because below 100 there are 9 twin odd nonprimes, e.g., 27 - 25 = 2.
		

Crossrefs

Cf. A093683, A006880, A007508.

Formula

a(n) = 10^n/2 - 2*A006880(n) + A007508(n) + 1. - Max Alekseyev, May 11 2005

Extensions

More terms from Max Alekseyev, May 11 2005

a(16) corrected and a(17)-a(18) added using the data at A006880 and A007508 by Amiram Eldar, Apr 29 2024