A067815 a(n) = gcd(n, floor(sqrt(n))).

1, 1, 1, 2, 1, 2, 1, 2, 3, 1, 1, 3, 1, 1, 3, 4, 1, 2, 1, 4, 1, 2, 1, 4, 5, 1, 1, 1, 1, 5, 1, 1, 1, 1, 5, 6, 1, 2, 3, 2, 1, 6, 1, 2, 3, 2, 1, 6, 7, 1, 1, 1, 1, 1, 1, 7, 1, 1, 1, 1, 1, 1, 7, 8, 1, 2, 1, 4, 1, 2, 1, 8, 1, 2, 1, 4, 1, 2, 1, 8, 9, 1, 1, 3, 1, 1, 3, 1, 1, 9

Offset: 1

Author

Reinhard Zumkeller, Feb 08 2002

Keywords

• nonn
• look

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000196, A073890, A075119.

Programs

Haskell

a067815 n = gcd n $ a000196 n  -- Reinhard Zumkeller, Jul 08 2014

Mathematica

a[n_] := GCD[n, Floor[Sqrt[n]]]; Array[a, 100] (* Amiram Eldar, Nov 19 2024 *)

PARI

a(n) = gcd(n, sqrtint(n)); \\ Altug Alkan, Dec 19 2017