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 A080330 #10 Jan 02 2022 13:16:12 %S A080330 0,0,1,1,2,2,3,2,3,2,6,2,6,2,7,1,5,4,11,9,3,6,8,10,12,2,3,4,6,18,19, %T A080330 13,16,3,17,20,2,3,2,24,6,11,3,8,2,15,2,3,2,15,20,2,8,27,13,25,3,6,18, %U A080330 2,15,2,15,25,11,6,10,2,17,3,2,15,2,3,27,20,15,20,2,25,27,42,2,15 %N A080330 Index in A002858 of the smaller of the two Ulam numbers that sum to the n-th Ulam number. %C A080330 The first two are zero because the Ulam sequence (A002858) is initialized for those terms. The terms of the sum are in A080328 and A080329 and the indices are in A080330 and A080331. %H A080330 Rémy Sigrist, <a href="/A080330/b080330.txt">Table of n, a(n) for n = 1..10000</a> %H A080330 Rémy Sigrist, <a href="/A080330/a080330.gp.txt">PARI program for A080330</a> %e A080330 The 11th Ulam number (26) is the sum of the 6th Ulam number (8) and the 10th Ulam number (18), so a(11)=6. %o A080330 (PARI) See Links section. %Y A080330 Cf. A002858, A080328, A080329, A080331. %K A080330 nonn %O A080330 1,5 %A A080330 _Jud McCranie_, Feb 15 2003