A057890 -id:A057890 - cp's OEIS frontend

A278862 Numbers that are not the sum of 2 or fewer terms from A057890.

157441, 177617, 178637, 226891, 374359, 900745, 1456223, 1526983, 1545227, 1817999, 2232815, 2274595, 2320643, 2336935, 2363383, 2404487, 2461559, 2536595, 2812451, 2877463, 2893769, 2910811, 2912446, 3046915, 3053999, 3090575, 3105319, 3382141

Offset: 1

Jeffrey Shallit, Dec 07 2016

nonn

Not known to be infinite. This list is complete up to 3,500,000.

Robert Israel, Table of n, a(n) for n = 1..262
Aayush Rajasekaran, Jeffrey Shallit, and Tim Smith, Sums of Palindromes: an Approach via Nested-Word Automata, preprint arXiv:1706.10206 [cs.FL], June 30 2017.

Cf. A057890.

# with A a list of terms < 2^d of A057890
B:= Array(0..2^d-1,datatype=integer[4]):
for a in A do B[a]:= 1 od:
C:= SignalProcessing:-Convolution(B,B):
select(t -> C[t+1] < 0.5, [$0..2^d-1]); # Robert Israel, Dec 08 2016

A062014 Duplicate of A057890.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 17, 18, 20, 21, 24, 27, 28, 30, 31, 32, 33

Offset: 0

dead

A057889 Bijective bit-reverse of n: keep the trailing zeros in the binary expansion of n fixed, but reverse all the digits up to that point.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 13, 12, 11, 14, 15, 16, 17, 18, 25, 20, 21, 26, 29, 24, 19, 22, 27, 28, 23, 30, 31, 32, 33, 34, 49, 36, 41, 50, 57, 40, 37, 42, 53, 52, 45, 58, 61, 48, 35, 38, 51, 44, 43, 54, 59, 56, 39, 46, 55, 60, 47, 62, 63, 64, 65, 66, 97, 68, 81, 98, 113

Offset: 0

Marc LeBrun, Sep 25 2000

The original name was "Bit-reverse of n, including as many leading as trailing zeros." - Antti Karttunen, Dec 25 2024
A permutation of integers consisting only of fixed points and pairs. a(n)=n when n is a binary palindrome (including as many leading as trailing zeros), otherwise a(n)=A003010(n) (i.e. n has no axis of symmetry). A057890 gives the palindromes (fixed points, akin to A006995) while A057891 gives the "antidromes" (pairs). See also A280505.
This is multiplicative in domain GF(2)[X], i.e. with carryless binary arithmetic. A193231 is another such permutation of natural numbers. - Antti Karttunen, Dec 25 2024

			a(6)=6 because 0110 is a palindrome, but a(11)=13 because 1011 reverses into 1101.

N. J. A. Sloane, Table of n, a(n) for n = 0..16384, May 30 2016 [First 8192 terms from _Ivan Neretin_, Jul 09 2015]
Index entries for sequences related to binary expansion of n
Index entries for sequences related to polynomials in ring GF(2)[X]
Index entries for sequences that are permutations of the natural numbers

Cf. A030101, A000265, A006519, A006995, A057890, A057891, A280505, A280508, A331166 [= min(n,a(n))], A366378 [k for which a(k) = k (mod 3)], A369044 [= A014963(a(n))].
Similar permutations for other bases: A263273 (base-3), A264994 (base-4), A264995 (base-5), A264979  (base-9).
Other related (binary) permutations: A056539, A193231.
Compositions of this permutation with other binary (or other base-related) permutations: A264965, A264966, A265329, A265369, A379471, A379472.
Compositions with permutations involving prime factorization: A245450, A245453, A266402, A266404, A293448, A366275, A366276.
Other derived permutations: A246200 [= a(3*n)/3], A266351, A302027, A302028, A345201, A356331, A356332, A356759, A366389.
See also A235027 (which is not a permutation).

Table[FromDigits[Reverse[IntegerDigits[n, 2]], 2]*2^IntegerExponent[n, 2], {n, 71}] (* Ivan Neretin, Jul 09 2015 *)

A030101(n) = if(n<1,0,subst(Polrev(binary(n)),x,2));
A057889(n) = if(!n,n,A030101(n/(2^valuation(n,2))) * (2^valuation(n, 2))); \\ Antti Karttunen, Dec 25 2024

def a(n):
    x = bin(n)[2:]
    y = x[::-1]
    return int(str(int(y))+(len(x) - len(str(int(y))))*'0', 2)
print([a(n) for n in range(101)]) # Indranil Ghosh, Jun 11 2017

def A057889(n): return int(bin(n>>(m:=(~n&n-1).bit_length()))[-1:1:-1],2)<Chai Wah Wu, Dec 25 2024

a(n) = A030101(A000265(n)) * A006519(n), with a(0)=0.

Clarified the name with May 30 2016 comment from N. J. A. Sloane, and moved the old name to the comments - Antti Karttunen, Dec 25 2024

A061917 Either a palindrome or becomes a palindrome if trailing 0's are omitted.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 20, 22, 30, 33, 40, 44, 50, 55, 60, 66, 70, 77, 80, 88, 90, 99, 100, 101, 110, 111, 121, 131, 141, 151, 161, 171, 181, 191, 200, 202, 212, 220, 222, 232, 242, 252, 262, 272, 282, 292, 300, 303, 313, 323, 330, 333, 343, 353, 363, 373, 383, 393, 400, 404

Offset: 1

N. J. A. Sloane, Jun 27 2001

Numbers that are palindromes when written with a suitable number of leading zeros. - Jeppe Stig Nielsen, Jan 17 2022

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Cf. A002113, A057890, A057891.

a061917 n = a061917_list !! (n-1)
a061917_list = filter chi [0..] where
   chi x = zs == reverse zs where
      zs = dropWhile (== '0') $ reverse $ show x
-- Reinhard Zumkeller, Sep 25 2011

PaleQ[n_Integer, base_Integer] := Module[{idn, trim = n/base^IntegerExponent[n, base]}, idn = IntegerDigits[trim, base]; idn == Reverse[idn]]; Select[Range[0, 500], PaleQ[#, 10] &] (* Lei Zhou, Dec 13 2013 *)
Join[{0},Select[Range[500],PalindromeQ[FromDigits[Drop[IntegerDigits[#],-IntegerExponent[#,10]]]]&]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, May 27 2017 *)

isOK(k)=k==0||fromdigits(Vecrev(digits(k)))==k/10^valuation(k,10) \\ Jeppe Stig Nielsen, Jan 17 2022

def ispal(s): return s == s[::-1]
def ok(n): s = str(n); return ispal(s) or ispal(s.rstrip('0'))
print([k for k in range(405) if ok(k)]) # Michael S. Branicky, Jan 17 2022

A136522(A004151(a(n))) = 1. - Reinhard Zumkeller, Sep 25 2011

Corrected by Ray Chandler, Jun 08 2009

A280505 The palindromic kernel of n in base 2 (with carryless GF(2)[X] factorization): a(n) = A091255(n,A057889(n)).

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1, 12, 1, 14, 15, 16, 17, 18, 1, 20, 21, 2, 3, 24, 1, 2, 27, 28, 3, 30, 31, 32, 33, 34, 7, 36, 1, 2, 5, 40, 1, 42, 3, 4, 45, 6, 1, 48, 7, 2, 51, 4, 3, 54, 1, 56, 5, 6, 1, 60, 1, 62, 63, 64, 65, 66, 1, 68, 1, 14, 3, 72, 73, 2, 15, 4, 3, 10, 7, 80, 1, 2, 9, 84, 85, 6, 1, 8, 3, 90, 1, 12, 93, 2, 5, 96, 1, 14, 99, 4, 9, 102, 1, 8, 15, 6

Offset: 1

Antti Karttunen, Jan 09 2017

a(n) = the maximal GF(2)[X]-divisor of n which in base 2 is either a palindrome or becomes a palindrome if trailing 0's are omitted.
More precisely: a(n) = the unique term m of A057890 for which A280500(n,m) > 0 and A091222(m) >= A091222(k) for all such terms k of A057890 for which A280500(n,k) > 0.
All terms are in A057890 and each term of A057890 occurs an infinite number of times.

Cf. A048720, A057889, A057890, A091222, A091255, A280501, A280503, A280506.

(define (A280505 n) (A091255bi n (A057889 n))) ;; A091255bi implements the 2-argument GF(2)[X] GCD-function (A091255).

a(n) = A091255(n,A057889(n)).
Other identities. For all n >= 1:
a(A057889(n)) = a(n).
A048720(a(n), A280506(n)) = n.

A057891 In base 2, neither a palindrome nor becomes a palindrome if trailing 0's are omitted.

Original entry on oeis.org

11, 13, 19, 22, 23, 25, 26, 29, 35, 37, 38, 39, 41, 43, 44, 46, 47, 49, 50, 52, 53, 55, 57, 58, 59, 61, 67, 69, 70, 71, 74, 75, 76, 77, 78, 79, 81, 82, 83, 86, 87, 88, 89, 91, 92, 94, 95, 97, 98, 100, 101, 103, 104, 105, 106, 109, 110, 111, 113, 114, 115, 116, 117, 118

Offset: 1

Marc LeBrun, Sep 25 2000

These could be called "asymmetric bit strings".
Fixed pairs of A057889, complement of A057890.
If these numbers are converted to their binary polynomial, one of the roots of that polynomial will have absolute values other than 1 or 0. For example 11 = 2^3 + 2^1 + 2^0, the absolute values of the roots of x^3 + x + 1 are 0.682328... and 1.21061... which are not 1 or 0, so 11 is in the sequence. The first number with this property which is not a term is A057890(53) = 107. - Benedict W. J. Irwin, Sep 07 2017 and Andrey Zabolotskiy, Oct 13 2017

			11 is included because 1011 is asymmetrical, but 12 is not because 001100 is a palindrome.

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Cf. A061917, A006995. Complement of A057890.

Cf. A030101, A000265, A006519, A057889.

a057891 n = a057891_list !! (n-1)
a057891_list = filter ((== 0) . a178225 . a000265) [1..]
-- Reinhard Zumkeller, Oct 21 2011

A030101(A030101(n)) != A030101(n). - David Wilson, Jun 09 2009, Jun 18 2009

A178225(A000265(a(n))) = 0. - Reinhard Zumkeller, Oct 21 2011

Edited by N. J. A. Sloane, Jun 09 2009 at the suggestion of Ray Chandler

A-numbers in formula corrected by R. J. Mathar, Jun 18 2009

A280506 Nonpalindromic part of n in base 2 (with carryless GF(2)[X] factorization): a(n) = A280500(n,A280505(n)).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 11, 1, 13, 1, 1, 1, 1, 1, 19, 1, 1, 11, 13, 1, 25, 13, 1, 1, 11, 1, 1, 1, 1, 1, 13, 1, 37, 19, 11, 1, 41, 1, 25, 11, 1, 13, 47, 1, 11, 25, 1, 13, 19, 1, 55, 1, 13, 11, 59, 1, 61, 1, 1, 1, 1, 1, 67, 1, 69, 13, 61, 1, 1, 37, 13, 19, 59, 11, 25, 1, 81, 41, 11, 1, 1, 25, 87, 11, 55, 1, 91, 13, 1, 47, 19, 1, 97, 11, 1, 25, 13, 1, 103

Offset: 1

Antti Karttunen, Jan 09 2017

a(n) = number obtained when the maximal base-2 palindromic divisor of n, A280505(n), is divided out of n with carryless GF(2)[X] factorization (see examples of A280500 for the explanation).

Apart from 1, all terms are present in A164861 (form their proper subset).

Cf. A000265, A048720, A057889, A057891, A164861, A280500, A280502, A280504, A280508, A280509.

Cf. A057890 (positions of ones).

(define (A280506 n) (A280500bi n (A280505 n))) ;; Code for A280500bi given in A280500.

a(n) = A280500(n,A280505(n)).
Other identities. For all n >= 1:
a(2n) = a(A000265(n)) = a(n).
A048720(a(n), A280505(n)) = n.

Erroneous claim removed from comments by Antti Karttunen, May 13 2018

A327971 Bitwise XOR of trajectories of rule 30 and its mirror image, rule 86, when both are started from a lone 1 cell: a(n) = A110240(n) XOR A265281(n).

Original entry on oeis.org

0, 0, 10, 20, 130, 396, 2842, 4420, 38610, 124220, 684490, 1385044, 8891330, 26281036, 192525274, 269101060, 2454365330, 8588410876, 43860512138, 89059958420, 551714970626, 1663794165260, 12235920695450, 19683098342340, 164315052318034, 538162708968636, 2894532467106378, 6192136868790228, 37503903254935874, 114926395086966988, 814341599153559130

Offset: 0

Antti Karttunen, Oct 03 2019

nonn

Each term is a binary palindrome when its trailing zeros (in base 2) are omitted, that is, a term of A057890.

Compare the binary string illustrations drawn for the first 1024 terms of this sequence and for A327976, which has almost the same definition.

Antti Karttunen, Table of n, a(n) for n = 0..1023
Antti Karttunen, Terms up to a(255) drawn as binary strings, with 1 bit = 3x3 pixels resolution
Antti Karttunen, Terms up to a(1023) drawn as binary strings, with 1 bit = 1 pixel resolution
Index entries for sequences related to binary expansion of n
Index entries for sequences related to cellular automata

Cf. A003987, A030101, A057890, A110240, A265281, A280508, A328106 (binary weight of terms).

Cf. also A327972, A327973, A327976, A328103, A328104 for other such combinations.

A269160(n) = bitxor(n, bitor(2*n, 4*n)); \\ From A269160.
A110240(n) = if(!n,1,A269160(A110240(n-1)));
A269161(n) = bitxor(4*n, bitor(2*n, n));
A265281(n) = if(!n,1,A269161(A265281(n-1)));
A327971(n) = bitxor(A110240(n), A265281(n));

A030101(n) = if(n<1,0,subst(Polrev(binary(n)),x,2));
A327971write(up_to) = { my(s=1, n=0); for(n=0,up_to, write("b327971.txt", n, " ", bitxor(s, A030101(s))); s = A269160(s)); };

def A269160(n): return(n^((n<<1)|(n<<2)))
def A269161(n): return((n<<2)^((n<<1)|n))
def genA327971():
    '''Yield successive terms of A327971.'''
    s1 = 1
    s2 = 1
    while True:
       yield (s1^s2)
       s1 = A269160(s1)
       s2 = A269161(s2)

a(n) = A110240(n) XOR A265281(n).
a(n) = A280508(A110240(n)) = A110240(n) XOR A030101(A110240(n)).
a(n) = A280508(A265281(n)) = A265281(n) XOR A030101(A265281(n)).
For n >= 1, a(n) = (1/2) * (A327973(n-1) XOR A327976(n-1)).

A280508 a(n) = n XOR A057889(n).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 6, 0, 0, 0, 0, 0, 10, 0, 0, 12, 10, 0, 10, 12, 0, 0, 10, 0, 0, 0, 0, 0, 18, 0, 12, 20, 30, 0, 12, 0, 30, 24, 0, 20, 18, 0, 18, 20, 0, 24, 30, 0, 12, 0, 30, 20, 12, 0, 18, 0, 0, 0, 0, 0, 34, 0, 20, 36, 54, 0, 0, 24, 34, 40, 20, 60, 54, 0, 20, 24, 54, 0, 0, 60, 34, 48, 20, 0, 54, 40, 0, 36, 34, 0, 34, 36, 0, 40, 54, 0, 20, 48

Offset: 0

Antti Karttunen, Jan 09 2017

Cf. A003987, A057889, A280505, A280506, A280507, A280509.

Cf. A057890 (positions of zeros).

(define (A280508 n) (A003987bi n (A057889 n))) ;; Where A003987bi implements A003987 (bitwise-XOR).

a(n) = A003987(n,A057889(n)) = n XOR A057889(n).
Other identities. For all n >= 0:
a(A057889(n)) = a(n).

A233010 In balanced ternary notation, either a palindrome or becomes a palindrome if trailing 0's are omitted.

Original entry on oeis.org

0, 1, 3, 4, 7, 9, 10, 12, 13, 16, 21, 27, 28, 30, 36, 39, 40, 43, 48, 52, 61, 63, 73, 81, 82, 84, 90, 91, 103, 108, 112, 117, 120, 121, 124, 129, 144, 156, 160, 183, 189, 196, 208, 219, 243, 244, 246, 252, 270, 273, 280, 292, 309, 324, 328, 336, 351, 360, 363

Offset: 1

Lei Zhou, Dec 13 2013

Symmetric strings of -1, 0, and 1, including as many leading as trailing zeros.

			10 is included since in balanced ternary notation 10 = (101)_bt is a palindrome;
144 is included since 144 = (1TT100)_bt, where we use T to represent -1.  When trailing zeros removed, 1TT1 is a palindrome.

Lei Zhou, Table of n, a(n) for n = 1..10000

Cf. A002113, A061917, A006995, A057890, A134027

BTDigits[m_Integer, g_] :=
Module[{n = m, d, sign, t = g},
  If[n != 0, If[n > 0, sign = 1, sign = -1; n = -n];
   d = Ceiling[Log[3, n]]; If[3^d - n <= ((3^d - 1)/2), d++];
   While[Length[t] < d, PrependTo[t, 0]]; t[[Length[t] + 1 - d]] = sign;
   t = BTDigits[sign*(n - 3^(d - 1)), t]]; t];
BTpaleQ[n_Integer] := Module[{t, trim = n/3^IntegerExponent[n, 3]},
  t = BTDigits[trim, {0}]; t == Reverse[t]];
Select[Range[0, 363], BTpaleQ[#] &]

cp's OEIS Frontend

A278862 Numbers that are not the sum of 2 or fewer terms from A057890.

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A062014 Duplicate of A057890.

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A057889 Bijective bit-reverse of n: keep the trailing zeros in the binary expansion of n fixed, but reverse all the digits up to that point.

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A061917 Either a palindrome or becomes a palindrome if trailing 0's are omitted.

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A280505 The palindromic kernel of n in base 2 (with carryless GF(2)[X] factorization): a(n) = A091255(n,A057889(n)).

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A057891 In base 2, neither a palindrome nor becomes a palindrome if trailing 0's are omitted.

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A280506 Nonpalindromic part of n in base 2 (with carryless GF(2)[X] factorization): a(n) = A280500(n,A280505(n)).

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A327971 Bitwise XOR of trajectories of rule 30 and its mirror image, rule 86, when both are started from a lone 1 cell: a(n) = A110240(n) XOR A265281(n).

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