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 A001042 M0743 N0279 #37 Jul 02 2025 16:01:54
%S A001042 1,2,3,5,16,231,53105,2820087664,7952894429824835871,
%T A001042 63248529811938901240357985099443351745,
%U A001042 4000376523371723941902615329287219027543200136435757892789536976747706216384
%N A001042 a(n) = a(n-1)^2 - a(n-2)^2.
%C A001042 The next term has 152 digits. - _Franklin T. Adams-Watters_, Jun 11 2009
%D A001042 Archimedeans Problems Drive, Eureka, 27 (1964), 6.
%D A001042 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
%D A001042 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A001042 Reinhard Zumkeller, <a href="/A001042/b001042.txt">Table of n, a(n) for n = 0..13</a>
%H A001042 A. V. Aho and N. J. A. Sloane, <a href="https://web.archive.org/web/2024*/https://www.fq.math.ca/Scanned/11-4/aho-a.pdf">Some doubly exponential sequences</a>, Fibonacci Quarterly, Vol. 11, No. 4 (1973), pp. 429-437.
%H A001042 A. V. Aho and N. J. A. Sloane, <a href="/A000058/a000058.pdf">Some doubly exponential sequences</a>, Fibonacci Quarterly, Vol. 11, No. 4 (1973), pp. 429-437 (original plus references that F.Q. forgot to include - see last page!)
%H A001042 R. K. Guy, <a href="/A002186/a002186.pdf">Letters to N. J. A. Sloane, June-August 1968</a>
%H A001042 R. P. Loh, A. G. Shannon, A. F. Horadam, <a href="/A000969/a000969.pdf">Divisibility Criteria and Sequence Generators Associated with Fermat Coefficients</a>, Preprint, 1980.
%H A001042 <a href="/index/Aa#AHSL">Index entries for sequences of form a(n+1)=a(n)^2 + ...</a>
%F A001042 a(n) ~ c^(2^n), where c = 1.1853051643868354640833201434870139866230288004895868726506278977814490371... . - _Vaclav Kotesovec_, Dec 17 2014
%t A001042 RecurrenceTable[{a[0]==1,a[1]==2,a[n]==a[n-1]^2-a[n-2]^2},a,{n,0,12}] (* _Harvey P. Dale_, Jan 11 2013 *)
%o A001042 (Haskell)
%o A001042 a001042 n = a001042_list !! n
%o A001042 a001042_list = 1 : 2 : zipWith (-) (tail xs) xs
%o A001042 where xs = map (^ 2) a001042_list
%o A001042 -- _Reinhard Zumkeller_, Dec 16 2013
%Y A001042 Cf. A001146, A000278, A000283, A058182, A007018.
%Y A001042 Cf. A064236 (numbers of digits).
%K A001042 nonn,nice,easy
%O A001042 0,2
%A A001042 _N. J. A. Sloane_, _R. K. Guy_
%E A001042 More terms from _James Sellers_, Sep 19 2000.