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 A120611 #6 May 14 2015 02:52:09 %S A120611 1,2,3,4,7,8,15,19,20,27,31,32,47,48,66,72,90,111,115,116,123,127,128, %T A120611 175,183,187,188,242,245,253,254,384,610,613,614,617,618,624,690,826, %U A120611 836,862,865,866,869,870,891,922,925,926,929,930,982,985,986,989,990 %N A120611 Sum of previous term and preceding divisors. %H A120611 Ivan Neretin, <a href="/A120611/b120611.txt">Table of n, a(n) for n = 1..10000</a> %F A120611 a(1) = 1, a(2) = 2, for n>=2, a(n+1) = a(n) + sum_{1<=k<n, a(k) divides a(n)} a(k). %t A120611 a = {1, 2}; Do[AppendTo[a, Plus @@ Intersection[a, Divisors[a[[-1]]]]], {n, 3, 57}]; a (* _Ivan Neretin_, May 13 2015 *) %Y A120611 Cf. A120610, A007497. %K A120611 nonn %O A120611 1,2 %A A120611 _Franklin T. Adams-Watters_, Jun 16 2006