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A174260
Prime numbers p such that the concatenation p//1331 is a prime number.
5
23, 29, 53, 101, 113, 239, 281, 311, 347, 353, 389, 401, 431, 617, 641, 647, 743, 797, 821, 827, 863, 911, 941, 1049, 1283, 1319, 1373, 1439, 1481, 1487, 1493, 1511, 1583, 1613, 1667, 1709, 1721, 1733, 1823, 1949
OFFSET
1,1
COMMENTS
Necessarily (as sod(1331) = 3 * 2 + 2): p = 6 * k - 1
See comments and references for A174213
EXAMPLE
231331 = prime(20545) => p(1) = 23 = prime(9)
291331 = prime(25334) => p(2) = 29 = prime(10)
MATHEMATICA
Select[Prime[Range[300]], PrimeQ[1331+10000#]&] (* Harvey P. Dale, Jun 22 2013 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Mar 14 2010
STATUS
approved