A224905 Smallest k such that (10^n+k, 10^n+k+2) and (10^(n+1)+k, 10^(n+1)+k+2) are two pairs of twin primes.
1, 49, 91, 1117, 2929, 721, 1819, 37237, 30979, 30967, 29629, 6457, 53269, 27727, 271159, 556651, 190489, 62797, 105259, 784777, 290659, 1320829, 438037, 1019317, 333991, 248371, 226609, 671227, 384571, 1573537, 366841, 954391, 1701247, 540811, 1105291
Offset: 1
Keywords
Examples
10^1+1=11 prime as 13 10^2+1=101 prime as 103 so a(1)=1.
Links
- Pierre CAMI, Table of n, a(n) for n = 1..76
Programs
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Mathematica
sk[n_]:=Module[{k=1},While[!AllTrue[{10^n+k,10^n+k+2,10^(n+1)+k,10^(n+1)+k+2},PrimeQ],k++];k]; Array[sk,35] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, May 09 2020 *)