A331896 Positive numbers all of whose divisors are negabinary palindromes (A331891).

1, 3, 5, 7, 11, 17, 21, 23, 31, 43, 51, 77, 85, 103, 127, 155, 211, 217, 233, 257, 301, 341, 479, 635, 683, 739, 771, 857, 889, 937, 1117, 1229, 1285, 1333, 1367, 1799, 1951, 2111, 2159, 2383, 2395, 2459, 2731, 2827, 3187, 3251, 3347, 3937, 4001, 4273, 4369

Offset

1,2

Links

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

Example

21 is a term since all the divisors of 21, {1, 3, 7, 21}, are palindromes in negabinary representation: {1, 111, 11011, 10101}.

Mathematica

negabin[n_] := negabin[n] = If[n==0, 0, negabin[Quotient[n-1, -2]]*10 + Mod[n, 2]]; nbPalinQ[n_] := PalindromeQ @ negabin[n]; negaBinAllDivPalQ[n_] := nbPalinQ[n] && AllTrue[Most @ Divisors[n], nbPalinQ]; Select[Range[5000], negaBinAllDivPalQ]

Crossrefs

Cf. A039724, A062687, A329419, A331891.

Sequence in context: A152998 A222176 A331891 * A108539 A170886 A361823

Adjacent sequences: A331893 A331894 A331895 * A331897 A331898 A331899

Keyword

nonn,base

Author

Amiram Eldar, Jan 30 2020

Status

approved