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 A060260 #12 Oct 03 2021 04:51:54 %S A060260 55,75,141,164,184,199,358,371,380,432,559,702,745,808,825,858,882, %T A060260 1077,1097,1279,1299,1303,1328,1408,1431,1486,1502,1558,1654,1702, %U A060260 1724,1744,1768,1820,1835,1873,1901,1905,1953,1977,2050,2148,2216,2220,2267 %N A060260 Numbers k such that prime(k), prime(k+1) and prime(k+2) have 10 as a primitive root, but prime(k-1) and prime(k+3) do not. %C A060260 A prime p has 10 as a primitive root iff the length of the period of the decimal expansion of 1/p is p-1. %H A060260 Amiram Eldar, <a href="/A060260/b060260.txt">Table of n, a(n) for n = 1..10000</a> %t A060260 test[p_] := MultiplicativeOrder[10, p]===p-1; Select[Range[2, 2500], test[Prime[ # ]]&&test[Prime[ #+1]]&&test[Prime[ #+2]]&&!test[Prime[ #-1]]&&!test[Prime[ #+3]]&] %Y A060260 The corresponding primes are in A060261. %Y A060260 Cf. A001913, A002371, A060259, A060262. %K A060260 nonn %O A060260 1,1 %A A060260 _Jeff Burch_, Mar 23 2001 %E A060260 Edited by _Dean Hickerson_, Jun 17 2002