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A065566
Numbers k such that floor((5/4)^(k+1))/floor((5/4)^k) = 5/4.
2
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
1,1
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.)
FORMULA
Is it true that lim_{n->infinity} a(n)/n = 6?
PROG
(PARI): for(n=1, 700, if(floor((5/4)^(n+1))/floor((5/4)^n)==5/4, print1(n, ", ")))
(PARI) { n=0; f=5/4; for (m=1, 10^9, if ((floor(f^(m + 1))/floor(f^m)) == f, write("b065566.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Oct 22 2009
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Nov 30 2001
EXTENSIONS
More terms from Jason Earls, Dec 03 2001
Edited by N. J. A. Sloane, May 24 2008
STATUS
approved