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%I #22 Aug 22 2024 02:31:27
%S 1,3,21,105,4305,21525,5316675,3291021825,38046409656325181475
%N a(1) = 1. a(n) = the smallest positive multiple of a(n-1) with exactly n 1's in its binary representation.
%C Each term is odd.
%C 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
%C The sequence is infinite (see AMM links). - _Max Alekseyev_, Aug 21 2024
%H Max Alekseyev, <a href="/A140451/b140451.txt">Table of n, a(n) for n = 1..10</a>
%H M. A. Alekseyev, <a href="https://doi.org/10.1080/00029890.2018.1483682">Problem 12058</a>, American Mathematical Monthly 125:7 (2018), 660.
%H A. Stadler, <a href="https://doi.org/10.1080/00029890.2020.1705076">Solution to problem 12058</a>, American Mathematical Monthly 127:3 (2020), 278.
%Y Cf. A000120.
%K base,nonn,changed
%O 1,2
%A _Leroy Quet_, Jul 21 2008
%E First 8 terms calculated by _R. J. Mathar_ and _Jack Brennen_.
%E a(9) from _Max Alekseyev_, Jul 22 2008
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