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 A103729 #3 Oct 12 2012 14:40:23 %S A103729 1,5,13,41,61,113,145,221,365,421,613,761,841,1013,1301,1625,1741, %T A103729 2113,2381,2521,2965,3281,3785,4513,4901,5101,5513,5725,6161,7813, %U A103729 8321,9113,9385,10805,11101,12013,12961,13613,14621,15665,16021 %N A103729 Column k=2 sequence of array A103728. %C A103729 It is clear that the a(n) are natural numbers since only odd primes appear in the formula below. %F A103729 a(n)=A103728(n+2, 2)=(1 + (p(n+2)-1)*binomial(p(n+2)-1, 2))/p(n+2), with p(n):=A000040(n) (n-th prime). %F A103729 a(n)= (5 - 4*p(n+2) + p(n+2)^2)/2 = sum(A103718(k, m)*p(n+2)^m, m=0..2)/2. %K A103729 nonn,easy %O A103729 0,2 %A A103729 _Wolfdieter Lang_, Feb 24 2005