A065566 Numbers k such that floor((5/4)^(k+1))/floor((5/4)^k) = 5/4.

7, 15, 17, 21, 25, 34, 52, 56, 59, 68, 74, 78, 99, 104, 111, 117, 118, 119, 124, 127, 129, 135, 136, 141, 145, 157, 162, 172, 179, 181, 184, 189, 190, 203, 204, 206, 209, 211, 212, 222, 226, 228, 245, 247, 250, 256, 258, 283, 291, 302, 315, 318, 327, 328, 331

Offset: 1

Author

Benoit Cloitre, Nov 30 2001

Keywords

• nonn

Comments

Also, numbers k such that (5^(k+1) mod 4^(k+1))/(5^k mod 4^k)=5, or A138589(n+1)/A138589(n) = 5. (See the Mathar link in A139768.)

Links

• Zak Seidov, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A065554, A138589, A139768.

Programs

PARI

isok(k) = { my(f=5/4); floor(f^(k + 1))/floor(f^k) == f } \\ Harry J. Smith, Oct 22 2009

Formula

Is it true that lim_{n->infinity} a(n)/n = 6?

Extensions

More terms from Jason Earls, Dec 03 2001

Edited by N. J. A. Sloane, May 24 2008