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 A064220 #7 May 01 2022 13:17:46
%S A064220 4,18,12,12,120,168,72,78,810,312,90,138,270,948,408,192,960,1920,738,
%T A064220 4698,810,1872,6978,2058,3222,570,870,390,9708,14118,9378,6822,8730,
%U A064220 2250,1008,8052,732,5400,2910,5982,2688,16758,1908,258,762,1488,12678
%N A064220 Least k such that k*11^n +/- 1 are twin primes.
%t A064220 Do[ k = 1; While[ ! PrimeQ[ k*11^n + 1 ] || ! PrimeQ[ k*11^n - 1 ], k++ ]; Print[ k ], {n, 0, 50} ]
%t A064220 lk[n_]:=Module[{c=11^n,k=1},While[!PrimeQ[k*c+1]||!PrimeQ[k*c-1],k++];k]; Array[lk,50,0] (* _Harvey P. Dale_, Jun 15 2019 *)
%Y A064220 Cf. A063983, A064213, A064214, A064215. A064217, A064218, A064221.
%K A064220 nonn
%O A064220 0,1
%A A064220 _Robert G. Wilson v_, Sep 21 2001
%E A064220 Offset corrected by _Georg Fischer_, May 01 2022