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 A085815 #12 Jul 14 2025 12:56:35
%S A085815 2,1,1,0,3,2,11,28,13,12,29,62,1,10,1,30,27,40,73,42,63,90,29,8,61,
%T A085815 120,37,20,41,20,1,66,283,66,27,146,1,222,1,8,77,190,173,18,1,50,149,
%U A085815 50,29,66,31,26,23,10,29,150,99,330,81,356,53,102,7,126,123,10,227,526,117,96
%N A085815 Least k such that A056830(n) + k is prime, where A056830 = alternate digits 1 and 0.
%H A085815 Harvey P. Dale, <a href="/A085815/b085815.txt">Table of n, a(n) for n = 0..500</a>
%e A085815 a(7)=28 because 1010101 + 28 = 1010129, a prime.
%t A085815 Table[Module[{k=0,d=FromDigits[PadRight[{},n,{1,0}]]},While[!PrimeQ[d+k],k++];k],{n,0,70}] (* _Harvey P. Dale_, Jul 14 2025 *)
%K A085815 nonn,base
%O A085815 0,1
%A A085815 _Jason Earls_, Jul 25 2003