A124049 a(n) = c is least number such that 10^n/2 -/+ c are primes.

0, 3, 9, 81, 123, 57, 87, 243, 69, 63, 189, 231, 1569, 381, 231, 1443, 1113, 321, 339, 1353, 363, 519, 1323, 1503, 741, 1221, 957, 1053, 339, 5931, 2121, 2301, 2031, 4773, 4737, 10281, 1317, 129, 3873, 1443, 387, 11769, 8271, 5337, 2883, 7137, 8193, 8493

Offset: 1

Author

Hans Havermann and Zak Seidov, Nov 03 2006

Keywords

• nonn

Comments

Related to Goldbach pairs of 10^n: a(n)=10^n/2 -A124450(n) Lesser of pair of closest primes whose sum is 10^n. Cf. A124013 Lesser of pair of most widely separated primes whose sum is 10^n, A065577 Number of Goldbach partitions of 10^n

All terms are divisible by 3 - see A108163.

Examples

			Next terms up to n = 101: 14637, 9897,
6471, 183, 8043, 6921,6699, 29127, 3663, 12537, 3777,
6741, 2253, 561, 3783, 26979, 16491, 6543, 10683,
1749, 6417, 38871, 22767, 62403, 8631, 4497, 20739,
453, 16731, 25293, 4341, 37467,
55323,4587,37083,24717,6687,8763,22551,29367,37881,14301,8637,34101,22179,26811,7059,1647
		

Crossrefs

Cf. A065577, A124013, A124450.

Programs

Mathematica

lnc[n_]:=Module[{c=0,t=10^n/2},While[!AllTrue[t+{c,-c},PrimeQ],c++];c]; Array[ lnc,50] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Dec 21 2014 *)