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Search: id:A140451
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A140451 a(1) = 1. a(n) = the smallest positive multiple of a(n-1) with exactly n 1's in its binary representation. +0
1
1, 3, 21, 105, 4305, 21525, 5316675, 3291021825, 38046409656325181475 (list; graph; listen)
OFFSET

1,2

COMMENT

First 8 terms calculated by Richard Mathar and Jack Brennen.

Each term is odd.

Can it be proved that there always is a positive multiple of each a(n-1) that has exactly n binary 1's? Or is the {a(k)} sequence finite?

a(10) <= 1 + 2^100 + 2^236 + 2^238 + 2^341 + 2^542 + 2^566 + 2^568 + 2^674 + 2^723.

= 441252181048159767719627961769263015304713273001222391692260944948404967249\

52505691843697819270690248905739332527064430387464361936830982164199090227218\

467520354158302900132818171857506562986336159915978303038159847425. - Max Alekseyev, Oct 12 2008

LINKS

Leroy Quet, Home Page (listed in lieu of email address)

CROSSREFS

Sequence in context: A134057 A128281 A034268 this_sequence A054147 A043012 A122120

Adjacent sequences: A140448 A140449 A140450 this_sequence A140452 A140453 A140454

KEYWORD

base,more,nonn

AUTHOR

Leroy Quet Jul 21 2008

EXTENSIONS

a(9) from Max Alekseyev, Jul 22 2008

page 1

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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