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 A185457 #39 May 10 2020 07:53:37
%S A185457 1,4,24,336,354144,116749235904,22940770664883067253376,
%T A185457 182503181432559739767250904458105698387204864
%N A185457 a(n) = abs( Im((2+i)^(2^n)) ).
%C A185457 The next term is too large to be displayed here.
%C A185457 Old name was: Leg of primitive Pythagorean triangle generated by repeated application of the basic formula y(n) = 2*x(n-1)*y(n-1), x(1)=2, y(1)=1.
%H A185457 Alois P. Heinz, <a href="/A185457/b185457.txt">Table of n, a(n) for n = 0..11</a>
%F A185457 a(n) = abs( Im((2+i)^(2^n)) ).
%e A185457 y(2)=24 since x(1)=3, y(1)=4 are the two legs of Pythagorean triangle obtained by p=2, q=1; second iteration p=3, q=4 gives 2*3*4=24.
%p A185457 a:= n-> abs(Im((2+I)^(2^n))):
%p A185457 seq(a(n), n=0..8); # _Alois P. Heinz_, Apr 25 2013
%t A185457 Table[Abs[Im[(2 + I)^(2^n)]], {n, 0, 10}] (* _G. C. Greubel_, Jul 07 2017 *)
%o A185457 (PARI) a(n) = abs(imag((2+I)^(2^n))); \\ _Joerg Arndt_, Apr 25 2013
%o A185457 (Python)
%o A185457 from sympy import im, I
%o A185457 def a(n): return abs(im((2 + I)**(2**n)))
%o A185457 print([a(n) for n in range(11)]) # _Indranil Ghosh_, Jul 08 2017
%Y A185457 Cf. A176594, A120905.
%Y A185457 Cf. A099456 ( imaginary part of (2+i)^n ).
%K A185457 nonn,less
%O A185457 0,2
%A A185457 _Carmine Suriano_, Feb 04 2011
%E A185457 Better name from _Joerg Arndt_, Apr 25 2013