login
This site is supported by donations to The OEIS Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A177869 Integers divisible by their number of digits in binary. 2

%I

%S 1,2,6,8,12,20,25,30,36,42,48,54,60,70,77,84,91,98,105,112,119,126,

%T 128,136,144,152,160,168,176,184,192,200,208,216,224,232,240,248,261,

%U 270,279,288,297,306,315,324,333,342,351,360,369,378,387,396,405

%N Integers divisible by their number of digits in binary.

%H Daniel Arribas, <a href="/A177869/b177869.txt">Table of n, a(n) for n = 1..1000</a>

%e 105 is 1101001 in base 2 (length of 7); 105 / 7 is 15.

%t Select[Range[410], IntegerQ[#/Length[IntegerDigits[#, 2]]] &] (* _Alonso del Arte_, Dec 13 2010 *)

%o (Python) import math

%o for n in range(1, 1000):

%o .if not n % int(math.log(n, 2) + 1): print n # Garcia

%o (Haskell)

%o base_weight b g n | n == 0 = 0 | otherwise = (base_weight b g (n `div` b)) + (g $ n `mod` b)

%o interesting b g = filter f [1..] where f n = n `mod` (base_weight b g n) == 0

%o bin_interesting g = interesting 2 g

%o weights l n | (n >=0) && ((length l) > fromInteger n) = l !! fromInteger n | otherwise = 0

%o cnst = weights [1, 1]

%o let sequence = bin_interesting cnst -- Victor S. Miller, Oct 17 2011

%o (PARI) for(d=1, 9, forstep(n=(2^(d-1)+d-1)\d*d, 2^d-1, d, print1(n", "))) \\ _Charles R Greathouse IV_, Oct 17 2011

%Y Base 10 equivalent is A098952.

%K nonn,base,changed

%O 1,2

%A _Grant Garcia_, Dec 13 2010

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 9 00:32 EST 2019. Contains 329871 sequences. (Running on oeis4.)