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 A104512 #19 Mar 31 2021 22:31:06 %S A104512 0,0,1,0,2,1,3,0,2,1,5,3,6,2,1,0,8,3,9,2,1,4,11,7,3,5,2,1,14,4,15,0,3, %T A104512 7,2,1,18,8,4,6,20,3,21,2,1,10,23,15,4,8,6,3,26,2,1,5,7,13,29,4,30,14, %U A104512 3,0,2,1,33,5,9,7,35,4,36,17,3,6,2,1,39,14,5,19,41,7,4,20,12,3,44,2,1,8,13 %N A104512 a(n) is the minimum number that is the first of k > 1 consecutive integers whose sum equals n, or 0 if impossible. %D A104512 Alfred S. Posamentier, Math Charmers, Tantalizing Tidbits for the Mind, Prometheus Books, NY, 2003, page 67. %H A104512 Antti Karttunen, <a href="/A104512/b104512.txt">Table of n, a(n) for n = 1..16416</a> %F A104512 a(n)=0 iff n=2^k. %F A104512 a(n)=1 iff n is a triangular number (A000217). %e A104512 a(18) = 3 because 3+4+5+6 = 5+6+7 = 18 but 3 < 5. %t A104512 f[n_] := Block[{r = Ceiling[n/2]}, If[ IntegerQ[ Log[2, n]], 0, m = Range[r]; lst = Flatten[ Table[ m[[k]], {i, r}, {j, i + 1, r}, {k, i, j}], 1]; lst[[ Position[ Plus @@@ lst, n, 1, 1][[1, 1]], 1]]]]; Table[ f[n], {n, 93}] (* _Robert G. Wilson v_, Feb 25 2005 *) %o A104512 (PARI) A104512(n) = if(!bitand(n,n-1), 0, my(b,d,u=1+sqrtint(2*n)); for(k=0,n-2,b = binomial(k+1,2); forstep(j=min(n,k+u),k+2,-1, d = binomial(j+1,2) - b; if(d==n,return(1+k),if(d<n,break)))); (0)); \\ _Antti Karttunen_, Mar 30 2021 %Y A104512 Cf. A104513, A104514, A104515, A104516. %Y A104512 Cf. A118235. %K A104512 nonn,look %O A104512 1,5 %A A104512 Alfred S. Posamentier (asp2(AT)juno.com) and _Robert G. Wilson v_, Feb 23 2005