OFFSET
1,3
COMMENTS
All terms are odd. It follows from the definition and Kummer theorem on 2-adic order of binomial coefficients.
From Robert Israel, Aug 30 2017: (Start)
a(n) = 1 if n is a power of 2.
a(2^k+m) = a(2^k+m-1)*(1 + 2^k/m) if 1 <= m < 2^k. (End)
LINKS
Robert Israel, Table of n, a(n) for n = 1..3421
Vladimir Shevelev, On a Luschny question, arXiv:1708.08096 [math.NT], 2017.
FORMULA
a(n) = binomial(n, A053644(n)). - Michel Marcus, Dec 15 2018
EXAMPLE
For n=11, k=8. So a(n) = binomial(11,8) = 165.
MAPLE
seq(binomial(n, 2^ilog2(n)), n=1..100); # Robert Israel, Aug 30 2017
MATHEMATICA
Table[Binomial[n, 2^Floor@ Log2@ n], {n, 41}] (* Michael De Vlieger, Aug 29 2017 *)
PROG
(PARI) a(n) = binomial(n, 2^logint(n, 2)); \\ Michel Marcus, Dec 15 2018
CROSSREFS
KEYWORD
nonn,look
AUTHOR
Vladimir Shevelev, Aug 29 2017
EXTENSIONS
More precise definition from Michael De Vlieger, Aug 30 2017
STATUS
approved