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A104718

Concatenations of pairs of primes that differ by 8.

311, 513, 1119, 2331, 2937, 5361, 5967, 7179, 8997, 101109, 131139, 149157, 173181, 191199, 233241, 263271, 269277, 359367, 389397, 401409, 431439, 449457, 479487, 491499, 563571, 569577, 593601, 599607, 653661, 683691, 701709, 719727, 743751

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OFFSET

1,1

COMMENTS

There are no primes in this sequence after a(1) = 311, as all values thereafter are divisible by 3. Semiprimes in this sequence include: a(3) = 1119 = 3 * 373 a(6) = 5361 = 3 * 1787, a(8) = 7179 = 3 * 2393, a(9) = 8997 = 3 * 2999, a(10) = 101109 = 3 * 33703, a(13) = 173181 = 3 * 57727, a(15) = 233241 = 3 * 77747, a(17) = 269277 = 3 * 89759, a(21) = 431439 = 3 * 143813, a(26) = 569577 = 3 * 189859, a(35) = 821829 = 3 * 273943.

LINKS

Table of n, a(n) for n=1..33.

FORMULA

a(n) = A023202(n) concatenated with A023202(n)+8.

CROSSREFS

Cf. A000040, A001358, A023202, A103195, A103206, A104719.

Sequence in context: A142626 A142950 A323050 * A142576 A374103 A025024

Adjacent sequences: A104715 A104716 A104717 * A104719 A104720 A104721

KEYWORD

base,easy,nonn

AUTHOR

Jonathan Vos Post, Mar 20 2005

STATUS

approved

URL: https://oeis.org/A104718

⇱ A104718 - OEIS