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 A176721 #2 Mar 30 2012 18:40:52 %S A176721 2,30205,133050536,1713435083707,12173043638400828, %T A176721 151229306063970112979,1815272942608097141328160, %U A176721 16183327444272811414262846321,331634334544577293143126414662454 %N A176721 Partial sums of A047076. %C A176721 Partial sums of a(n+1) is the smallest palindromic prime containing exactly 2 more digits on each end than the previous term, with a(n) as a central substring. Can this partial sum ever be a palindromic prime? %F A176721 a(n) = SUM[i=1..n] A047076(i). %e A176721 a(8) = 2 + 30203 + 133020331 + 1713302033171 + 12171330203317121 + 151217133020331712151 + 1815121713302033171215181 + 16181512171330203317121518161 = 16183327444272811414262846321 is prime %Y A176721 Cf. A047076, A046485. %K A176721 base,nonn %O A176721 1,1 %A A176721 _Jonathan Vos Post_, Apr 25 2010