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 A231965 #39 Feb 16 2025 08:33:20
%S A231965 246,288,892,9020,11456,23480,52274,33686,190070,1741856,1668564,
%T A231965 7806762
%N A231965 Smallest integer starting a group of exactly n consecutive untouchable numbers (A005114) with term differences of 2.
%C A231965 Such n-tuplets from A005114 correspond to n+1 positive numbers interspersed with n zeros in A070015, and starting at a(n) - 1. For instance, a(4) = 892 is related to A070015(891) and consecutive values: 2661, 0, 4147, 0, 2945, 0, 1287, 0, 9757.
%H A231965 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/UntouchableNumber.html">Untouchable Number.</a>
%H A231965 Wikipedia, <a href="http://en.wikipedia.org/wiki/Untouchable_number">Untouchable number</a>
%e A231965 a(5) = 9020, because 9020, 9022, 9024, 9026, 9028 are untouchable, while 9018 and 9030 are not so (A001065). For examples with smaller n, see A231964 comments.
%o A231965 (PARI) oksucc(v, vi, n) = {for (i = 1, n-1, if (! vecsearch(v, vi+2*i, ) , return (0));); return(! vecsearch(v, vi-2) && !vecsearch(v, vi+2*n));}
%o A231965 a(n) = {v = readvec("untouchable.log"); for (i=1, #v, vi = v[i]; if (oksucc(v, vi, n), return(vi)););} \\ readvec reads the file obtained by keeping the second column of b005114.txt seen as a csv file.
%Y A231965 Cf. A001065, A005114, A231964.
%Y A231965 Cf. A110875 (analog for sigma(n)).
%K A231965 nonn,more
%O A231965 2,1
%A A231965 _Michel Marcus_, Nov 16 2013
%E A231965 a(10)-a(13) from _Donovan Johnson_, Nov 16 2013
%E A231965 Definition, data, and Pari script corrected by _Michel Marcus_ with _Donovan Johnson_, Nov 18 2013