A174260 - OEIS

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A174260

Prime numbers p such that the concatenation p//1331 is a prime number.

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

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OFFSET

1,1

COMMENTS

Necessarily (as sod(1331) = 3 * 2 + 2): p = 6 * k - 1

See comments and references for A174213

LINKS

Table of n, a(n) for n=1..40.

EXAMPLE

231331 = prime(20545) => p(1) = 23 = prime(9)

291331 = prime(25334) => p(2) = 29 = prime(10)

MATHEMATICA