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A331894 Positive numbers such that both their binary and negabinary representations are palindromic. 5
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
COMMENTS
Numbers of the form 2^(2*m-1) - 1 (A083420) and 2^(2*m) + 1 (A052539) are terms.
LINKS
EXAMPLE
7 is a term since the binary representation of 7, 111, and the negabinary representation of 7, 11011, are both palindromic.
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[#]}) &]
CROSSREFS
Intersection of A006995 and A331891.
Sequence in context: A122853 A137258 A053341 * A357234 A086086 A141772
KEYWORD
nonn,base
AUTHOR
Amiram Eldar, Jan 30 2020
STATUS
approved

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Last modified March 3 14:01 EST 2024. Contains 370512 sequences. (Running on oeis4.)