A108163 -id:A108163 - cp's OEIS frontend

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

Hans Havermann and Zak Seidov, Nov 03 2006

nonn

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.

			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

Cf. A065577, A124013, A124450.

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 *)

cp's OEIS Frontend

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

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