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 A221977 #12 Sep 18 2013 02:58:46
%S A221977 0,0,1,1,2,3,6,7,8,10,14,18,25,34,46,60,89,120,165,227,298,415,590,
%T A221977 821,1152,1606,2240,3188,4438,6208,8714,12280,17368,24560,34821,49413,
%U A221977 70581,100856,143955,205291,293061,419256,600213,858870,1230523,1764914,2532078
%N A221977 Number of primes of the form (x+1)^7 - x^7 less than 10^n.
%C A221977 Number of primes less than 10^n and equal to the difference of two consecutive seventh powers (x+1)^7 - x^7 = 7x(x+1)(x^2+x+1)^2+1 (A121618). Values of x = A121619 - 1. Sequence of number of primes less than 10^n and of the form (x+1)^7 - x^7 have similar characteristics to similar sequences for natural primes (A006880), cuban primes (A113478) and primes of the form (x+1)^5 - x^5 (A221846).
%H A221977 Vladimir Pletser, <a href="/A221977/b221977.txt">Table of n, a(n) for n = 1..50</a>
%t A221977 nn = 20; t = Table[0, {nn}]; n = 0; While[n++; p = (n + 1)^7 - n^7; p < 10^nn,If[PrimeQ[p], m = Ceiling[Log[10, p]]; t[[m]]++]]; Accumulate[t] (* _T. D. Noe_, Feb 04 2013 *)
%K A221977 nonn,base
%O A221977 1,5
%A A221977 _Vladimir Pletser_, Feb 02 2013