OFFSET
0,3
LINKS
Peter Kagey, Table of n, a(n) for n = 0..10000
EXAMPLE
13 in binary is 1101. So a(13) is the denominator of 1/4 + 1/3 + 1 = 19/12, since the binary digits at positions (from right to left) 1, 3 and 4 are each 1 and the other digits are 0.
MATHEMATICA
Table[Denominator@ Total@ MapIndexed[#1/ First@ #2 &, Reverse@ IntegerDigits[n, 2]], {n, 0, 79}] (* Michael De Vlieger, Aug 19 2017 *)
PROG
(PARI) a(n) = {my(b = Vecrev(binary(n))); denominator(sum(k=1, #b, b[k]/k)); } \\ Michel Marcus, Apr 18 2016
CROSSREFS
KEYWORD
easy,frac,nonn
AUTHOR
Leroy Quet, Feb 13 2006
EXTENSIONS
More terms from Joshua Zucker, May 03 2006
STATUS
approved