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A029471 Numbers n such that n divides the (left) concatenation of all numbers <= n written in base 2 (most significant digit on left). 141
1, 85, 145, 245, 1189, 356717, 19590671, 35741759 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

No other terms below 10^8.

LINKS

Table of n, a(n) for n=1..8.

Index entries for related sequences

MATHEMATICA

b = 2; c = {}; Select[Range[10^4], Divisible[FromDigits[c = Join[IntegerDigits[#, b], c], b], #] &] (* Robert Price, Mar 12 2020 *)

PROG

(Python)

from itertools import count

def a029471():

    total = 0

    power_of_two = 1

    index_of_two = 0

    length_of_string = 0

    for n in count(1):

        total += (n<<length_of_string)

        if n == power_of_two:

            power_of_two *= 2

            index_of_two += 1

        length_of_string += index_of_two

        if total % n == 0:

            yield n

# Christian Perfect, Feb 07 2014

CROSSREFS

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

Sequence in context: A259219 A273123 A239527 * A083750 A043684 A043574

Adjacent sequences:  A029468 A029469 A029470 * A029472 A029473 A029474

KEYWORD

nonn,base,hard,more

AUTHOR

Olivier Gérard

EXTENSIONS

One more term from Larry Reeves (larryr(AT)acm.org), Dec 03 2001

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

a(7)-a(8) from Max Alekseyev, May 12 2011

STATUS

approved

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Last modified October 25 06:05 EDT 2020. Contains 338011 sequences. (Running on oeis4.)