A109505 - OEIS

%I #37 Oct 09 2020 03:38:25

%S 1,422,174,-1,22830,9216772051242,234374,-1,-1

%N 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 a(10) <= 462850319999160398264270. - _David A. Corneth_, Sep 19 2020

%C 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 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 See A109473, the main entry for this sequence, for more information.

%Y Cf. A020754, A337914, A337915.

%K sign,hard,more

%O 1,2

%A _N. J. A. Sloane_, Aug 31 2005

%E a(6) corrected by _Don Reble_. - _N. J. A. Sloane_, Nov 25 2019