Original entry on oeis.org
7, 13, 29, 61, 101, 107, 199, 211, 229, 241, 419, 449, 467, 479, 769, 823, 829, 859, 991, 1009, 1021, 1571, 1601, 1637, 1667, 1697, 1733, 1811, 1847, 1877, 1901, 1907, 1931, 3079, 3109, 3229, 3271, 3307, 3331, 3457, 3499, 3529, 3541, 3547
Offset: 1
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lim:=1800: with(numtheory):A182624:={}:for n from 1 to lim do s:="": for d in divisors(n) do s:= cat(s,convert(convert(d, binary),string)): od: m:=convert(parse(s),decimal,binary):if(isprime(m))then A182624:=A182624 union {m};fi: od:
A182624:=sort(convert(A182624,list)):for n from 1 to nops(A182624) do if(A182624[n]>2*lim)then break:fi:printf("%d, ",A182624[n]):od: # Nathaniel Johnston, Apr 19 2011
A182621
a(n) is the concatenation of the binary numbers that are the divisors of n written in base 2.
Original entry on oeis.org
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
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.
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A182621[n_]:=FromDigits[Flatten[IntegerDigits[Divisors[n],2]]];Array[A182621,50] (* Paolo Xausa, Aug 31 2023 *)
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a(n) = fromdigits(concat(apply(binary,divisors(n)))); \\ Kevin Ryde, May 02 2023
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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
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A182621 = lambda n: Integer(''.join(d.str(base=2) for d in divisors(n))) # D. S. McNeil, Dec 19 2010
A182620
Triangle T(n,k) read by rows in which row n lists the divisors of n, written in base 2.
Original entry on oeis.org
1, 1, 10, 1, 11, 1, 10, 100, 1, 101, 1, 10, 11, 110, 1, 111, 1, 10, 100, 1000, 1, 11, 1001, 1, 10, 101, 1010, 1, 1011, 1, 10, 11, 100, 110, 1100, 1, 1101, 1, 10, 111, 1110, 1, 11, 101, 1111, 1, 10, 100, 1000, 10000, 1, 10001, 1, 10, 11
Offset: 1
The divisors of 10 are 1, 2, 5, 10 then row 10 lists the binary numbers 1, 10, 101, 1010.
Triangle begins:
1,
1, 10,
1, 11,
1, 10, 100,
1, 101,
1, 10, 11, 110,
1, 111,
1, 10, 100, 1000,
1, 11, 1001,
1, 10, 101, 1010,
1, 1011,
1, 10, 11, 100, 110, 1100,
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with(numtheory):for n from 1 to 10 do for d in divisors(n) do printf("%d, ",convert(d,binary)); od:printf("\n");od: # Nathaniel Johnston, Apr 19 2011
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Table[FromDigits[IntegerDigits[#,2]]&/@Divisors[n],{n,20}]//Flatten (* Harvey P. Dale, May 31 2018 *)
A182622
a(n) is the number whose binary representation is the concatenation of the divisors of n written in base 2.
Original entry on oeis.org
1, 6, 7, 52, 13, 222, 15, 840, 121, 858, 27, 28268, 29, 894, 991, 26896, 49, 113970, 51, 215892, 2037, 3446, 55, 14471576, 441, 3514, 3899, 217052, 61, 14538238, 63, 1721376, 7905, 13410, 7139, 926213284, 101, 13542, 8039, 221009192
Offset: 1
The divisors of 10 are 1, 2, 5, 10. Then 1, 2, 5, 10 written in base 2 are 1, 10, 101, 1010. The concatenation of 1, 10, 101, 1010 is 1101011010. Then a(10) = 858 because the binary number 1101011010 written in base 10 is 858.
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concatBits[n_] := FromDigits[Join @@ (IntegerDigits[#, 2]& /@ Divisors[n]), 2]; concatBits /@ Range[40](* Giovanni Resta, Nov 23 2010 *)
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a(n) = {my(cbd = []); fordiv(n, d, cbd = concat(cbd, binary(d));); fromdigits(cbd, 2);} \\ Michel Marcus, Jan 28 2017
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def A182622(n):
s=""
for i in range(1,n+1):
if n%i==0:
s+=bin(i)[2:]
return int(s,2) # Indranil Ghosh, Jan 28 2017
Showing 1-4 of 4 results.
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