A112757 Greatest common divisors of consecutive 5-smooth numbers.

1, 1, 1, 1, 1, 2, 1, 1, 2, 3, 1, 2, 2, 4, 1, 1, 3, 2, 4, 4, 5, 3, 2, 2, 6, 4, 8, 3, 5, 1, 9, 6, 4, 4, 12, 5, 1, 1, 9, 6, 10, 2, 18, 12, 8, 8, 9, 15, 3, 1, 2, 2, 18, 12, 20, 4, 36, 15, 3, 16, 5, 27, 18, 30, 6, 2, 4, 4, 36, 24, 25, 5, 8, 27, 45, 9, 3, 6, 32, 10, 54, 36, 60, 12, 4, 8, 8, 45, 9, 48, 15, 5

Offset

1,6

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..750 from Harvey P. Dale)

Formula

a(n) = gcd(A051037(n), A051037(n+1)).

Mathematica

GCD@@#&/@(Partition[Select[Range[2000], Max[Transpose[ FactorInteger[ #]] [[1]]]<6&], 2, 1]) (* Harvey P. Dale, Dec 24 2015 *)

Crossrefs

Cf. A051037, A112752.

Sequence in context: A240750 A181118 A179009 * A219794 A351469 A286334

Adjacent sequences: A112754 A112755 A112756 * A112758 A112759 A112760

Keyword

nonn

Author

Reinhard Zumkeller, Sep 18 2005

Status

approved