A229086 Numbers k such that the concatenation of the divisors of k written in base 2 is a palindromic number.

1, 3, 7, 11, 19, 31, 43, 67, 103, 127, 131, 199, 239, 307, 331, 379, 439, 463, 547, 683, 887, 911, 991, 1123, 1171, 1291, 1531, 1543, 1783, 1951, 2731, 2843, 3067, 3079, 3511, 3823, 4099, 5107, 5323, 5419, 5659, 5851, 6151, 6343, 6679, 6871, 6967, 7159, 8191

Offset: 1

Author

Jaroslav Krizek, Sep 13 2013

Keywords

• nonn
• base

Comments

Concatenation of the divisors of n written in base 2 = A182621.

Are there composite numbers with this property?

Conjecture: a(n) for n > 1 is not equal to A161387, sequence also contains composites.

The answer to the question above is Yes. The first two composites are 297883 and 476635. - T. D. Noe, Sep 17 2013

Examples

			The number 103 is in sequence because the concatenation of its divisors written in base 2 (1, 1100111) is palindromic number - 11100111.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A161387, A182621.

Programs

Mathematica

Select[Range[10000], (temp=Flatten[IntegerDigits[Divisors[#],2]]; temp==Reverse[temp])&]