A331894 Positive numbers such that both their binary and negabinary representations are palindromic.

0, 1, 3, 5, 7, 17, 21, 31, 51, 65, 85, 127, 195, 257, 273, 325, 341, 455, 511, 771, 819, 1025, 1105, 1285, 1365, 1799, 2047, 3075, 4097, 4161, 4369, 4433, 5125, 5189, 5397, 5461, 7175, 7967, 8191, 12291, 12483, 13107, 16385, 16705, 17425, 17745, 20485, 20805

Offset: 1

Author

Amiram Eldar, Jan 30 2020

Keywords

• nonn
• base

Comments

Numbers of the form 2^(2*m-1) - 1 (A083420) and 2^(2*m) + 1 (A052539) are terms.

Examples

			7 is a term since the binary representation of 7, 111, and the negabinary representation of 7, 11011, are both palindromic.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..1000

Crossrefs

Intersection of A006995 and A331891.

Cf. A039724, A095309.

Programs

Mathematica

negabin[n_] := negabin[n] = If[n==0, 0, negabin[Quotient[n-1, -2]]*10 + Mod[n, 2]]; Select[Range[0, 2*10^4], And @@ (PalindromeQ /@ {IntegerDigits[#, 2], negabin[#]}) &]