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 A183530 #13 May 02 2017 15:34:55 %S A183530 1,2,3,4,5,6,7,28,49,50,51,52,53,54,55,70,82,91,109,112,555,556,563, %T A183530 564,572,573,576,583,584,591,593,1103,1104,1105,1111,1112,1124,1632, %U A183530 1637,1642,1643,1648,1653,1654,1655,1656,1657,1660,1661,1662,1671,1672,2184 %N A183530 An Ulam-type sequence: a(n) = n if n<=7; for n>7, a(n) = least number > a(n-1) which is a unique sum of 7 distinct earlier terms. %C A183530 An Ulam-type sequence - see A002858 for further information. %H A183530 Alois P. Heinz, <a href="/A183530/b183530.txt">Table of n, a(n) for n = 1..500</a> %H A183530 <a href="/index/U#Ulam_num">Index entries for Ulam numbers</a> %e A183530 a(8) = 28 = 1 + ... + 7 = 7*8/2, because it is the least number >7 with a unique sum of 7 distinct earlier terms. %e A183530 a(9) = 49 = 1 + ... + 6 + 28 = 7^2, because it is the least number >28 with a unique sum of 7 distinct earlier terms. %p A183530 # see A183534 for programs. %Y A183530 Column k=7 of A183534. %Y A183530 Cf. A002858, A007086, A183527-A183533, A135737. %K A183530 nonn %O A183530 1,2 %A A183530 _Jonathan Vos Post_ and _Alois P. Heinz_, Jan 05 2011