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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.
1
1, 3, 21, 105, 4305, 21525, 5316675, 3291021825, 38046409656325181475
OFFSET
1,2
COMMENTS
Each term is odd.
a(10) = 2^617 + 2^529 + 2^527 + 2^401 + 2^352 + 2^284 + 2^240 + 2^239 + 2^154 + 1 has 186 decimal digits. - Max Alekseyev, Feb 04 2018
The sequence is infinite (see AMM links). - Max Alekseyev, Aug 21 2024
LINKS
M. A. Alekseyev, Problem 12058, American Mathematical Monthly 125:7 (2018), 660.
A. Stadler, Solution to problem 12058, American Mathematical Monthly 127:3 (2020), 278.
CROSSREFS
Cf. A000120.
Sequence in context: A134057 A128281 A034268 * A054147 A233582 A043012
KEYWORD
base,nonn
AUTHOR
Leroy Quet, Jul 21 2008
EXTENSIONS
First 8 terms calculated by R. J. Mathar and Jack Brennen.
a(9) from Max Alekseyev, Jul 22 2008
STATUS
approved