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 A247207 #13 Nov 29 2014 05:51:08
%S A247207 10,30,354,72354,4338079554,18448597098193370754,
%T A247207 340282370354622283774333836163326852354,
%U A247207 115792089237316207213755562747271079374483128445080168181132550891186006948354
%N A247207 4^(2^n) + 3^(2^n) + 2^(2^n) + 1.
%F A247207 a(n) = sum_{k = 1 .. 4} k^(2^n).
%F A247207 For all n > 1, a(n) = 54 mod 100.
%e A247207 a(2) = 4^4 + 3^4 + 2^4 + 1 = 256 + 81 + 16 + 1 = 354.
%e A247207 a(3) = 4^8 + 3^8 + 2^8 + 1 = 65536 + 6561 + 256 + 1 = 72354.
%t A247207 Table[1 + Sum[k^(2^n), {k, 2, 4}], {n, 0, 7}]
%Y A247207 Cf. A091775, A000855.
%K A247207 nonn,easy
%O A247207 0,1
%A A247207 _Alonso del Arte_, Nov 25 2014