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 A350349 #4 Dec 26 2021 14:15:46 %S A350349 1,2,3,4,6,7,8,9,11,12,14,15,16,17,19,20,21,22,25,26,27,28,30,31,32, %T A350349 33,35,36,38,39,42,43,44,45,47,48,49,50,52,53,55,56,57,58,60,61,62,63, %U A350349 66,67,68,69,71,72,73,74,76,77,80,81,82,83,85,86,87,88,90 %N A350349 Lexicographically earliest increasing sequence of positive integers such that the Hankel matrix of any odd number of consecutive terms is invertible. %H A350349 Wikipedia, <a href="https://en.wikipedia.org/wiki/Hankel_matrix">Hankel matrix</a> %o A350349 (Python) %o A350349 from sympy import Matrix %o A350349 from itertools import count %o A350349 def A350349_list(nmax): %o A350349 a=[1] %o A350349 for n in range(1,nmax): %o A350349 a.append(next(k for k in count(a[-1]+1) if all(Matrix((n-r)//2+1,(n-r)//2+1,lambda i,j:(a[r:]+[k])[i+j]).det()!=0 for r in range(n-2,-1,-2)))) %o A350349 return a %Y A350349 Cf. A350330, A350348, A350350. %K A350349 nonn %O A350349 1,2 %A A350349 _Pontus von Brömssen_, Dec 26 2021