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A182621 a(n) is the concatenation of the binary numbers that are the divisors of n written in base 2.

%I A182621 #33 Aug 31 2023 09:51:00
%S A182621 1,110,111,110100,1101,11011110,1111,1101001000,1111001,1101011010,
%T A182621 11011,110111001101100,11101,1101111110,1111011111,110100100010000,
%U A182621 110001,11011110100110010,110011,110100101101010100,11111110101,110101110110,110111,110111001101000110011000
%N A182621 a(n) is the concatenation of the binary numbers that are the divisors of n written in base 2.
%C A182621 a(n) is the concatenation of the numbers of row n of triangle A182620.  The first repeated element is a(15) = 1111011111 = a(479), where a(15) is the concatenation of 1, 11, 101 and 1111 but a(479) is the concatenation of 1 and 111011111. See A182620 and A182622 for more information.
%H A182621 Jaroslav Krizek, <a href="/A182621/b182621.txt">Table of n, a(n) for n = 1..500</a>
%e A182621 The divisors of 10 are 1, 2, 5, 10, which written in base 2 are 1, 10, 101, 1010. The concatenation of 1, 10, 101, 1010 is 1101011010, so a(10) = 1101011010.
%t A182621 A182621[n_]:=FromDigits[Flatten[IntegerDigits[Divisors[n],2]]];Array[A182621,50] (* _Paolo Xausa_, Aug 31 2023 *)
%o A182621 (Sage) A182621 = lambda n: Integer(''.join(d.str(base=2) for d in divisors(n))) # _D. S. McNeil_, Dec 19 2010
%o A182621 (Python)
%o A182621 from sympy import divisors
%o A182621 def a(n): return int("".join(bin(d)[2:] for d in divisors(n)))
%o A182621 print([a(n) for n in range(1, 25)]) # _Michael S. Branicky_, Apr 20 2022
%o A182621 (PARI) a(n) = fromdigits(concat(apply(binary,divisors(n)))); \\ _Kevin Ryde_, May 02 2023
%Y A182621 Cf. A007088, A027750, A182620, A182622, A182623, A182624, A182631.
%K A182621 nonn,base,easy,less
%O A182621 1,2
%A A182621 _Omar E. Pol_, Nov 22 2010