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

1, 110, 111, 110100, 1101, 11011110, 1111, 1101001000, 1111001, 1101011010, 11011, 110111001101100, 11101, 1101111110, 1111011111, 110100100010000, 110001, 11011110100110010, 110011, 110100101101010100, 11111110101, 110101110110, 110111, 110111001101000110011000

Offset

1,2

Comments

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.

Links

Jaroslav Krizek, Table of n, a(n) for n = 1..500

Example

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.

Mathematica

A182621[n_]:=FromDigits[Flatten[IntegerDigits[Divisors[n], 2]]]; Array[A182621, 50] (* Paolo Xausa, Aug 31 2023 *)

Prog

(Sage) A182621 = lambda n: Integer(''.join(d.str(base=2) for d in divisors(n))) # D. S. McNeil, Dec 19 2010
(Python)
from sympy import divisors
def a(n): return int("".join(bin(d)[2:] for d in divisors(n)))
print([a(n) for n in range(1, 25)]) # Michael S. Branicky, Apr 20 2022
(PARI) a(n) = fromdigits(concat(apply(binary, divisors(n)))); \\ Kevin Ryde, May 02 2023

Crossrefs

Cf. A007088, A027750, A182620, A182622, A182623, A182624, A182631.

Sequence in context: A287138 A288769 A112891 * A267254 A036230 A171236

Adjacent sequences: A182618 A182619 A182620 * A182622 A182623 A182624

Keyword

nonn,base,easy,less

Author

Omar E. Pol, Nov 22 2010

Status

approved