login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS").
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A061931 Numbers n such that n divides the (right) concatenation of all numbers <= n written in base 2 (most significant digit on right). 142
1, 3, 7, 39, 63, 523, 4983, 25007, 892217, 1142775, 1381311, 1751751 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

This sequence differs from A029495 in that all least significant zeros are removed before concatenation.

No more terms < 10^7. [Lars Blomberg, Oct 17 2011]

LINKS

Table of n, a(n) for n=1..12.

Index entries for related sequences

EXAMPLE

1234567 -> (1)(01)(11)(001)(101)(011)(111) base 2 -> 1111110111111 base 2 = 8127 and 7 divides 8127.

MATHEMATICA

b = 2; c = {}; Select[Range[10^4], Divisible[FromDigits[

c = Join[c, IntegerDigits[IntegerReverse[#, b], b]], b], #] &] (* Robert Price, Mar 07 2020 *)

CROSSREFS

Cf. A029447-A029470, A029471-A029494, A029495-A029518, A029519-A029542, A061931-A061954, A061955-A061978.

Sequence in context: A335812 A282427 A192198 * A057203 A056250 A113870

Adjacent sequences:  A061928 A061929 A061930 * A061932 A061933 A061934

KEYWORD

nonn,base,more

AUTHOR

Larry Reeves (larryr(AT)acm.org), May 24 2001

EXTENSIONS

Edited and updated by Larry Reeves (larryr(AT)acm.org), Apr 12 2002

a(9)-a(12) from Lars Blomberg, Oct 17 2011

STATUS

approved

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 3 02:56 EST 2020. Contains 338899 sequences. (Running on oeis4.)