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.
%I A268145 #14 Jan 27 2016 13:19:39
%S A268145 345,567,111213,171819,293031,414243,596061,717273,101102103,
%T A268145 107108109,137138139,149150151,179180181,191192193,197198199,
%U A268145 227228229,239240241,269270271,281282283,311312313,347348349,419420421,431432433,461462463,521522523,569570571,599600601
%N A268145 Twin prime pairs concatenated to their average in decimal representation (with the lesser twin prepended and the greater twin appended).
%C A268145 The lesser prime of a twin prime pair is prepended and the greater prime is appended to their average (nonprime, interprime).
%C A268145 a(n) mod 3 = 0, (See A095958).
%e A268145 a(1)=345: the lesser prime {3} of the first twin prime pair {3, 5} is prepended and the greater prime {5} is appended to their average {4}.
%e A268145 a(3)=111213: the lesser {11} of the 3rd twin prime pair {11, 13} is prepended and the greater prime {13} is appended to their average {12}.
%t A268145 UpToN[k_]:=FromDigits//@ StringJoin//@ ToString/@ {#-1, #, #+1} &/@ Select[ Table[ Prime[n]+1, {n, 2, PrimePi[k]}], PrimeQ[#+1] &]; UpToN[10000]
%Y A268145 Cf. A001097, A014574, A095958, A111875.
%K A268145 nonn,base,easy
%O A268145 1,1
%A A268145 _Mikk Heidemaa_, Jan 27 2016