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 A109505 #37 Oct 09 2020 03:38:25 %S A109505 1,422,174,-1,22830,9216772051242,234374,-1,-1 %N A109505 Consider the smallest pair of consecutive squarefree numbers (r,s) with gcd(r,s) = n; sequence gives values of r, or -1 if n is not squarefree. %C A109505 a(10) <= 462850319999160398264270. - _David A. Corneth_, Sep 19 2020 %C A109505 If n is odd then a(n) >= A020754(n-1). If n is even then a(n) >= A020754(2n-1). - _Jud McCranie_, Sep 30 2020 %e A109505 174 is squarefree, 177 is the next squarefree integer, and gcd(174,177) = 3; this is the first pair of consecutive squarefree numbers whose GCD is 3, so a(3)=174. - _Jud McCranie_, Nov 25 2019 %Y A109505 See A109473, the main entry for this sequence, for more information. %Y A109505 Cf. A020754, A337914, A337915. %K A109505 sign,hard,more %O A109505 1,2 %A A109505 _N. J. A. Sloane_, Aug 31 2005 %E A109505 a(6) corrected by _Don Reble_. - _N. J. A. Sloane_, Nov 25 2019