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 A129741 #14 May 25 2024 14:05:32
%S A129741 2,3,7,23,59,157,11,139,8209,9257,620297,983,4003,1847,9803,
%T A129741 1687054711,1433,33008447,83,101,113,51563,61,823,5381,20117,6329,
%U A129741 262650531833,197,10259,519606349,2621,11887,136667817691,13933,42591667,564188663,211,8802371
%N A129741 List of primitive prime divisors of the Somos-4 sequence (A006720) in their order of occurrence.
%C A129741 Read A006720 term-by-term, factorize each term, write down any primes not seen before.
%H A129741 T. D. Noe, <a href="/A129741/b129741.txt">Table of n, a(n) for n = 1..121</a> (from the first 49 terms)
%H A129741 G. Everest et al., <a href="http://www.jstor.org/stable/27642221">Primes generated by recurrence sequences</a>, Amer. Math. Monthly, 114 (No. 5, 2007), 417-431.
%t A129741 a[0] = a[1] = a[2] = a[3] = 1; a[n_] := a[n] = (a[n - 1] a[n - 3] + a[n - 2]^2)/a[n - 4]; t = Array[a, 30]; t2 = {}; ps = {}; Do[f = Transpose[FactorInteger[t[[n]]]][[1]]; c = Complement[f, ps]; t2 = Join[t2, c]; ps = Union[ps, c], {n, 4, 30}]; t2 (* _T. D. Noe_, Nov 19 2013 *)
%t A129741 DeleteDuplicates[DeleteCases[Flatten[FactorInteger[#][[;;,1]]&/@RecurrenceTable[{a[0]==a[1]== a[2]==a[3]==1,a[n]==(a[n-1]a[n-3]+a[n-2]^2)/a[n-4]},a,{n,30}]],1]] (* _Harvey P. Dale_, May 25 2024 *)
%Y A129741 Cf. A006720, A129739, A129740.
%Y A129741 Cf. A227199 (primes in this sequence).
%K A129741 nonn
%O A129741 1,1
%A A129741 _N. J. A. Sloane_, May 13 2007
%E A129741 Order of some of the terms corrected by _T. D. Noe_, Nov 19 2013