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 A286706 #16 Feb 16 2025 08:33:45
%S A286706 23,4567,78910111213,
%T A286706 25262728293031323334353637383940414243444546474849
%N A286706 Primes in A077309.
%C A286706 That is, primes formed from concatenation of k numbers starting with k.
%C A286706 Subsequence of A052087.
%C A286706 a(5) must be larger than A077309(2500).
%C A286706 A077309(k) is prime for k = {2, 4, 7, 25, ...}. - _Michael De Vlieger_, May 13 2017
%H A286706 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ConsecutiveNumberSequences.html">Consecutive Number Sequences</a>
%e A286706 The prime 4567 is a term since it is the concatenation of 4 decimal numbers beginning with the number 4. - _Michael De Vlieger_, May 13 2017
%t A286706 Select[Table[FromDigits@ Flatten@ Take[#, {n, n + (n - 1)}], {n, Ceiling[Length[#]/2]}], PrimeQ] &@ Array[IntegerDigits, 10^3] (* _Michael De Vlieger_, May 13 2017 *)
%Y A286706 Cf. A077309, A052087, A035333, A053067.
%K A286706 base,easy,nonn
%O A286706 1,1
%A A286706 _XU Pingya_, May 12 2017