cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A268146 Twin prime pairs concatenated to their average in decimal representation (the greater twin prepended, the lesser appended).

Original entry on oeis.org

543, 765, 131211, 191817, 313029, 434241, 616059, 737271, 103102101, 109108107, 139138137, 151150149, 181180179, 193192191, 199198197, 229228227, 241240239, 271270269, 283282281, 313312311, 349348347, 421420419, 433432431, 463462461, 523522521, 571570569, 601600599
Offset: 1

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Author

Mikk Heidemaa, Jan 27 2016

Keywords

Comments

The greater prime of a twin prime pair is prepended and the lesser one is appended to their average (nonprime, interprime).
a(n) mod 3 = 0, (See A095958).

Examples

			a(1)=543: the greater prime {5} of the first twin prime pair {3, 5} is prepended and the lesser prime {3} is appended to their average {4}.

Crossrefs

Cf. A001097, A014574, A095958, A111875, A268145.

Programs

  • Mathematica
    UpToN[k_]:=FromDigits//@ StringJoin//@ ToString/@ {#+1, #, #-1} &/@ Select[ Table[ Prime[n]+1, {n, 2, PrimePi[k]}], PrimeQ[#+1] &]; UpToN[10000]
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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