A048727 -id:A048727 - cp's OEIS frontend

A048730 Differences between A008589 (multiples of 7) and A048727, a(n) = ((n*7)-Xmult(n,7)).

0, 0, 0, 12, 0, 8, 24, 28, 0, 0, 16, 28, 48, 56, 56, 60, 0, 0, 0, 12, 32, 40, 56, 60, 96, 96, 112, 124, 112, 120, 120, 124, 0, 0, 0, 12, 0, 8, 24, 28, 64, 64, 80, 92, 112, 120, 120, 124, 192, 192, 192, 204, 224, 232, 248

Offset: 0

Antti Karttunen, Apr 26 1999

For n = binary n[k],n[k-1],...,n[0], bits a(n) = binary b[k+1],b[k],...,b[0] are b[i] = 1 when n[i-1] + n[i-2] + n[i-3] >= 2, so the majority bit 0 or 1 among the 3 bits of n below position i (with 0 bits below the radix point of n as necessary). This is since 7*n = 4*n + 2*n + n is n[i-1] + n[i-2] + n[i-3] at position i-1, and 4*n XOR 2*n XOR n is the same but no carry, so b[i] is the carry only. - Kevin Ryde, Mar 26 2021

Paolo Xausa, Table of n, a(n) for n = 0..8191

Positions of zeros are given by A048715. Cf. A048733, A342697.

Diagonal 7 of A061858.

A048730[n_] := 7*n - BitXor[n, 2*n, 4*n];
Array[A048730,100, 0] (* Paolo Xausa, Aug 06 2025 *)

a(n)=7*n - bitxor(n, bitxor(2*n, 4*n)) \\ Charles R Greathouse IV, Oct 03 2016

def A048730(n): return 7*n-(n^n<<1^n<<2) # Chai Wah Wu, Jun 29 2022

A284557 a(n) = A048727(n) mod 3.

Original entry on oeis.org

0, 1, 2, 0, 1, 0, 0, 0, 2, 0, 0, 1, 0, 2, 0, 0, 1, 2, 0, 1, 0, 2, 2, 2, 0, 1, 1, 2, 0, 2, 0, 0, 2, 0, 1, 2, 0, 2, 2, 2, 0, 1, 1, 2, 1, 0, 1, 1, 0, 1, 2, 0, 2, 1, 1, 1, 0, 1, 1, 2, 0, 2, 0, 0, 1, 2, 0, 1, 2, 1, 1, 1, 0, 1, 1, 2, 1, 0, 1, 1, 0, 1, 2, 0, 2, 1, 1, 1, 2, 0, 0, 1, 2, 1, 2, 2, 0, 1, 2, 0, 1, 0, 0, 0, 1, 2, 2, 0, 2, 1, 2, 2, 0, 1, 2, 0, 2, 1, 1, 1, 0

Offset: 0

Antti Karttunen, Apr 10 2017

Antti Karttunen, Table of n, a(n) for n = 0..8192
Index entries for sequences related to binary expansion of n

Row 3 of array A284270 (after the initial zero).

Cf. A048727, A284555 (positions of zeros), A284574, A284575.

def A284557(n): return (n^ n<<1 ^ n<<2) % 3 # Chai Wah Wu, Jun 29 2022

(define (A284557 n) (modulo (A048727 n) 3))
(define (A284557 n) (A284270bi 3 n)) ;; For A284270bi see A284270.

a(n) = A048727(n) mod 3.

A048720 Multiplication table {0..i} X {0..j} of binary polynomials (polynomials over GF(2)) interpreted as binary vectors, then written in base 10; or, binary multiplication without carries.

Original entry on oeis.org

0, 0, 0, 0, 1, 0, 0, 2, 2, 0, 0, 3, 4, 3, 0, 0, 4, 6, 6, 4, 0, 0, 5, 8, 5, 8, 5, 0, 0, 6, 10, 12, 12, 10, 6, 0, 0, 7, 12, 15, 16, 15, 12, 7, 0, 0, 8, 14, 10, 20, 20, 10, 14, 8, 0, 0, 9, 16, 9, 24, 17, 24, 9, 16, 9, 0, 0, 10, 18, 24, 28, 30, 30, 28, 24, 18, 10, 0, 0, 11, 20, 27, 32, 27, 20, 27, 32, 27, 20, 11, 0

Offset: 0

Antti Karttunen, Apr 26 1999

Essentially same as A091257 but computed starting from offset 0 instead of 1.
Each polynomial in GF(2)[X] is encoded as the number whose binary representation is given by the coefficients of the polynomial, e.g., 13 = 2^3 + 2^2 + 2^0 = 1101_2 encodes 1*X^3 + 1*X^2 + 0*X^1 + 1*X^0 = X^3 + X^2 + X^0. - Antti Karttunen and Peter Munn, Jan 22 2021
To listen to this sequence, I find instrument 99 (crystal) works well with the other parameters defaulted. - Peter Munn, Nov 01 2022

			Top left corner of array:
  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0 ...
  0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 ...
  0  2  4  6  8 10 12 14 16 18 20 22 24 26 28 30 ...
  0  3  6  5 12 15 10  9 24 27 30 29 20 23 18 17 ...
  ...
From _Antti Karttunen_ and _Peter Munn_, Jan 23 2021: (Start)
Multiplying 10 (= 1010_2) and 11 (= 1011_2), in binary results in:
     1011
  *  1010
  -------
   c1011
  1011
  -------
  1101110  (110 in decimal),
and we see that there is a carry-bit (marked c) affecting the result.
In carryless binary multiplication, the second part of the process (in which the intermediate results are summed) looks like this:
    1011
  1011
  -------
  1001110  (78 in decimal).
(End)

Alois P. Heinz, Antidiagonals n = 0..200, flattened
Antti Karttunen, Scheme-program for computing this sequence.
N. J. A. Sloane, Transforms: Maple implementation of binary eXclusive OR (XORnos).
Index entries for sequences related to carryless arithmetic
Index entries for sequences related to polynomials in ring GF(2)[X]

Cf. A051776 (Nim-product), A091257 (subtable).
Carryless multiplication in other bases: A325820 (3), A059692 (10).
Ordinary {0..i} * {0..j} multiplication table: A004247 and its differences from this: A061858 (which lists further sequences related to presence/absence of carry in binary multiplication).
Carryless product of the prime factors of n: A234741.
Binary irreducible polynomials ("X-primes"): A014580, factorization table: A256170, table of "X-powers": A048723, powers of 3: A001317, rearranged subtable with distinct terms (comparable to A054582): A277820.
See A014580 for further sequences related to the difference between factorization into GF(2)[X] irreducibles and ordinary prime factorization of the integer encoding.
Row/column 3: A048724 (even bisection of A003188), 5: A048725, 6: A048726, 7: A048727; main diagonal: A000695.
Associated additive operation: A003987.
Equivalent sequences, as compared with standard integer multiplication: A048631 (factorials), A091242 (composites), A091255 (gcd), A091256 (lcm), A280500 (division).
See A091202 (and its variants) and A278233 for maps from/to ordinary multiplication.
See A115871, A115872 and A277320 for tables related to cross-domain congruences.

trinv := n -> floor((1+sqrt(1+8*n))/2); # Gives integral inverses of the triangular numbers
# Binary multiplication of nn and mm, but without carries (use XOR instead of ADD):
Xmult := proc(nn,mm) local n,m,s; n := nn; m := mm; s := 0; while (n > 0) do if(1 = (n mod 2)) then s := XORnos(s,m); fi; n := floor(n/2); # Shift n right one bit. m := m*2; # Shift m left one bit. od; RETURN(s); end;

trinv[n_] := Floor[(1 + Sqrt[1 + 8*n])/2];
Xmult[nn_, mm_] := Module[{n = nn, m = mm, s = 0}, While[n > 0, If[1 == Mod[n, 2], s = BitXor[s, m]]; n = Floor[n/2]; m = m*2]; Return[s]];
a[n_] := Xmult[(trinv[n] - 1)*((1/2)*trinv[n] + 1) - n, n - (trinv[n]*(trinv[n] - 1))/2];
Table[a[n], {n, 0, 100}] (* Jean-François Alcover, Mar 16 2015, updated Mar 06 2016 after Maple *)

up_to = 104;
A048720sq(b,c) = fromdigits(Vec(Pol(binary(b))*Pol(binary(c)))%2, 2);
A048720list(up_to) = { my(v = vector(1+up_to), i=0); for(a=0, oo, for(col=0, a, i++; if(i > up_to, return(v)); v[i] = A048720sq(col, a-col))); (v); };
v048720 = A048720list(up_to);
A048720(n) = v048720[1+n]; \\ Antti Karttunen, Feb 15 2021

a(n) = Xmult( (((trinv(n)-1)*(((1/2)*trinv(n))+1))-n), (n-((trinv(n)*(trinv(n)-1))/2)) );
T(2b, c)=T(c, 2b)=T(b, 2c)=2T(b, c); T(2b+1, c)=T(c, 2b+1)=2T(b, c) XOR c - Henry Bottomley, Mar 16 2001
For n >= 0, A003188(2n) = T(n, 3); A003188(2n+1) = T(n, 3) XOR 1, where XOR is the bitwise exclusive-or operator, A003987. - Peter Munn, Feb 11 2021

A269160 Formula for Wolfram's Rule 30 cellular automaton: a(n) = n XOR (2n OR 4n).

Original entry on oeis.org

0, 7, 14, 13, 28, 27, 26, 25, 56, 63, 54, 53, 52, 51, 50, 49, 112, 119, 126, 125, 108, 107, 106, 105, 104, 111, 102, 101, 100, 99, 98, 97, 224, 231, 238, 237, 252, 251, 250, 249, 216, 223, 214, 213, 212, 211, 210, 209, 208, 215, 222, 221, 204, 203, 202, 201, 200, 207, 198, 197, 196, 195, 194, 193, 448, 455, 462

Offset: 0

Antti Karttunen, Feb 20 2016

nonn

Take n, write it in binary, see what Rule 30 would do to that state, convert it to decimal: that is a(n). For example, we can see in A110240 that 7 = 111_2 becomes 25 = 11001_2 under Rule 30, which is shown here by a(7) = 25. - N. J. A. Sloane, Nov 25 2016
The sequence is injective: no value occurs more than once.
Fibbinary numbers (A003714) give all integers n>=0 for which a(n) = A048727(n) and for which a(n) = A269161(n).

Antti Karttunen, Table of n, a(n) for n = 0..16383
Eric Weisstein's World of Mathematics, Rule 30
Index entries for sequences related to cellular automata
Index to Elementary Cellular Automata

Cf. A003714, A003986, A003987, A057889, A070939.
Cf. A110240 (iterates starting from 1).
Cf. A269162 (left inverse).
Cf. A269163 (same sequence sorted into ascending order).
Cf. A269164 (values missing from this sequence).
Cf. also A048727, A269161.

a[n_] := BitXor[n, BitOr[2n, 4n]]; Table[a[n], {n, 0, 100}] (* Jean-François Alcover, Feb 23 2016 *)

a(n) = bitxor(n, bitor(2*n, 4*n)); \\ Michel Marcus, Feb 23 2016

def A269160(n): return n^(n<<1 | n<<2) # Chai Wah Wu, Jun 29 2022

(define (A269160 n) (A003987bi n (A003986bi (* 4 n) (* 2 n)))) ;; Where A003986bi and A003987bi are implementation of dyadic functions giving bitwise-OR (A003986) and bitwise-XOR (A003987) of their arguments.

a(n) = n XOR (2n OR 4n) = A003987(n, A003986(2*n, 4*n)).
Other identities. For all n >= 0:
a(2*n) = 2*a(n).
a(n) = A057889(A269161(A057889(n))). [Rule 30 is the mirror image of rule 86.]
A269162(a(n)) = n.
For all n >= 1:
A070939(a(n)) - A070939(n) = 2. [The binary length of a(n) is two bits longer than that of n for all nonzero values.]
G.f.: (3*x + 2*x^2 +x^3)/(1 - x^4) + Sum_{k>=1}(2^(k + 1)*x^(2^(k - 1))/((1 + x^(2^(k + 1)))*(1 - x))). - Miles Wilson, Jan 24 2025

A048725 a(n) = Xmult(n,5) or rule90(n,1).

Original entry on oeis.org

0, 5, 10, 15, 20, 17, 30, 27, 40, 45, 34, 39, 60, 57, 54, 51, 80, 85, 90, 95, 68, 65, 78, 75, 120, 125, 114, 119, 108, 105, 102, 99, 160, 165, 170, 175, 180, 177, 190, 187, 136, 141, 130, 135, 156, 153, 150, 147, 240, 245, 250, 255, 228, 225, 238, 235, 216, 221, 210

Offset: 0

Antti Karttunen, Apr 26 1999

The orbit of 1 under iteration of this function is the Sierpinski gasket A038183. It is called "rule 90" because the 8 bits of 90 = 01011010 in binary give bit k of the result as function of the value in {0,...,7} made out of bits k,k+1,k+2 of the input (i.e., floor(input / 2^k) mod 8). - M. F. Hasler, Oct 09 2017

			   n (in binary) | 4n [binary] | n XOR 4n [binary] | [decimal] = a(n)
          0      |        0    |           0       |        0
          1      |      100    |         101       |        5
         10      |     1000    |        1010       |       10
         11      |     1100    |        1111       |       15
        100      |    10000    |       10100       |       20
        101      |    10100    |       10001       |       17
   etc.

Alois P. Heinz, Table of n, a(n) for n = 0..16383

Cf. A048720, A048705, A048710, A048724, A048727, A048729.
Cf. A038183.
Cf. A353167 (terms sorted).

a:= n-> Bits[Xor](n*4, n):
seq(a(n), n=0..120);  # Alois P. Heinz, Aug 24 2019

Table[ BitXor[4n, n], {n, 0, 60}] (* Robert G. Wilson v, Jul 06 2006 *)

a(n)=bitxor(n,4*n) \\ Charles R Greathouse IV, Oct 03 2016

def A048725(n): return n^ n<<2 # Chai Wah Wu, Jun 29 2022

a(n) = n XOR n*2 XOR (n XOR n*2)*2 = A048724(A048724(n)). - Reinhard Zumkeller, Nov 12 2004

a(n) = n XOR (4n). - M. F. Hasler, Oct 09 2017

A277320 Square array A(r,c) = A048720(A065621(r), c), read by descending antidiagonals as A(1,1), A(1,2), A(2,1), A(1,3), A(2,2), A(3,1), etc.

Original entry on oeis.org

1, 2, 2, 3, 4, 7, 4, 6, 14, 4, 5, 8, 9, 8, 13, 6, 10, 28, 12, 26, 14, 7, 12, 27, 16, 23, 28, 11, 8, 14, 18, 20, 52, 18, 22, 8, 9, 16, 21, 24, 57, 56, 29, 16, 25, 10, 18, 56, 28, 46, 54, 44, 24, 50, 26, 11, 20, 63, 32, 35, 36, 39, 32, 43, 52, 31, 12, 22, 54, 36, 104, 42, 58, 40, 100, 46, 62, 28, 13, 24, 49, 40, 101, 112, 49, 48, 125, 104, 33, 56, 21

Offset: 1

Antti Karttunen, Nov 01 2016

			The top left corner of the array:
   1,   2,   3,   4,   5,   6,   7,   8,   9,  10,  11,  12
   2,   4,   6,   8,  10,  12,  14,  16,  18,  20,  22,  24
   7,  14,   9,  28,  27,  18,  21,  56,  63,  54,  49,  36
   4,   8,  12,  16,  20,  24,  28,  32,  36,  40,  44,  48
  13,  26,  23,  52,  57,  46,  35, 104, 101, 114, 127,  92
  14,  28,  18,  56,  54,  36,  42, 112, 126, 108,  98,  72
  11,  22,  29,  44,  39,  58,  49,  88,  83,  78,  69, 116
   8,  16,  24,  32,  40,  48,  56,  64,  72,  80,  88,  96
  25,  50,  43, 100, 125,  86,  79, 200, 209, 250, 227, 172
  26,  52,  46, 104, 114,  92,  70, 208, 202, 228, 254, 184
  31,  62,  33, 124,  99,  66,  93, 248, 231, 198, 217, 132
  28,  56,  36, 112, 108,  72,  84, 224, 252, 216, 196, 144
  21,  42,  63,  84,  65, 126, 107, 168, 189, 130, 151, 252
  22,  44,  58,  88,  78, 116,  98, 176, 166, 156, 138, 232
  19,  38,  53,  76,  95, 106, 121, 152, 139, 190, 173, 212
  16,  32,  48,  64,  80,  96, 112, 128, 144, 160, 176, 192
  49,  98,  83, 196, 245, 166, 151, 392, 441, 490, 475, 332
  50, 100,  86, 200, 250, 172, 158, 400, 418, 500, 454, 344
  55, 110,  89, 220, 235, 178, 133, 440, 399, 470, 481, 356

Transpose: A277199.
Main diagonal: A277699.
Row 1: A000027, Row 3: A048727.
Column 1: A065621, Column 3: A277823, Column 5: A277825.
Cf. A277820 (array obtained by selecting only the columns with an index A001317(k), k=0..).
Cf. A048720, A115872.

(define (A277320 n) (A277320bi (A002260 n) (A004736 n)))
(define (A277320bi row col) (A048720bi (A065621 row) col))

A(r,c) = A048720(A065621(r), c).

A048715 Binary expansion matches (100(0))(0|1|10)?; or, Zeckendorf-like expansion of n using recurrence f(n) = f(n-1) + f(n-3).

Original entry on oeis.org

0, 1, 2, 4, 8, 9, 16, 17, 18, 32, 33, 34, 36, 64, 65, 66, 68, 72, 73, 128, 129, 130, 132, 136, 137, 144, 145, 146, 256, 257, 258, 260, 264, 265, 272, 273, 274, 288, 289, 290, 292, 512, 513, 514, 516, 520, 521, 528, 529, 530, 544, 545, 546, 548, 576, 577, 578, 580

Offset: 0

Antti Karttunen, Mar 30 1999

No more than one 1-bit in each bit triple.
All terms satisfy A048727(n) = 7*n.
Constructed from A000930 in the same way as A003714 is constructed from A000045.
It appears that n is in the sequence if and only if C(7n,n) is odd (cf. A003714). - Benoit Cloitre, Mar 09 2003
The conjecture by Benoit is correct. This is easily proved using the well-known result that the multiplicity with which a prime p divides C(n+m,n) is the number of carries when adding n+m in base p. - Franklin T. Adams-Watters, Oct 06 2009
Appears to be the set of numbers x such that (x AND 5*x) = x and (x OR 3*x)/x = 3. - Gary Detlefs, Jun 08 2024

G. C. Greubel, Table of n, a(n) for n = 0..1275
Sebastian Karlsson, Walnut code that verifies the conjectures of Paul D. Hanna
Walnut can be downloaded from https://cs.uwaterloo.ca/~shallit/walnut.html.
Index entries for sequences defined by congruent products between domains N and GF(2)[X]
Index entries for sequences defined by congruent products under XOR
Index entries for 2-automatic sequences.

Subsequence of A048716.

Cf. A003726, A004742, A004743, A004744, A048717, A048718, A048719, A048730, A048733, A115422, A115423, A115424.

Reap[Do[If[OddQ[Binomial[7n, n]], Sow[n]], {n, 0, 400}]][[2, 1]]
(* Second program: *)
filterQ[n_] := With[{bb = IntegerDigits[n, 2]}, !MatchQ[bb, {_, 1, 0, 1, _}|{_, 1, 1, _}]];
Select[Range[0, 580], filterQ] (* Jean-François Alcover, Dec 31 2020 *)

is(n)=!bitand(n, 6*n) \\ Charles R Greathouse IV, Oct 03 2016

for my $k (0..580) { print "$k, " if sprintf("%b", $k) =~ m{^(100(0)*)*(0|1|10)?$}; } # Georg Fischer, Jun 26 2021

import re
def ok(n): return re.fullmatch('(100(0)*)*(0|1|10)?', bin(n)[2:]) != None
print(list(filter(ok, range(581)))) # Michael S. Branicky, Jun 26 2021

a(0) = 0, a(n) = (2^(invfoo(n)-1))+a(n-foo(invfoo(n))), where foo(n) is foo(n-1) + foo(n-3) (A000930) and invfoo is its "integral" (floored down) inverse.
a(n) XOR 6*a(n) = 7*a(n); 3*a(n) XOR 4*a(n) = 7*a(n); 3*a(n) XOR 5*a(n) = 6*a(n); (conjectures). - Paul D. Hanna, Jan 22 2006
The conjectures can be verified using the Walnut theorem-prover (see links). - Sebastian Karlsson, Dec 31 2022

Definition corrected by Georg Fischer, Jun 26 2021

A269161 Formula for Wolfram's Rule 86 cellular automaton: a(n) = 4n XOR (2n OR n).

Original entry on oeis.org

0, 7, 14, 11, 28, 27, 22, 19, 56, 63, 54, 51, 44, 43, 38, 35, 112, 119, 126, 123, 108, 107, 102, 99, 88, 95, 86, 83, 76, 75, 70, 67, 224, 231, 238, 235, 252, 251, 246, 243, 216, 223, 214, 211, 204, 203, 198, 195, 176, 183, 190, 187, 172, 171, 166, 163, 152, 159, 150, 147, 140, 139, 134, 131, 448, 455, 462, 459

Offset: 0

Antti Karttunen, Feb 20 2016

nonn

The sequence is injective: no value occurs more than once.

Fibbinary numbers (A003714) give all integers n>=0 for which a(n) = A048727(n) and for which a(n) = A269160(n).

Antti Karttunen, Table of n, a(n) for n = 0..16383
Eric Weisstein's World of Mathematics, Rule 30
Index entries for sequences related to cellular automata
Index to Elementary Cellular Automata

Cf. A003714, A003986, A003987, A057889, A163617.
Cf. A265281 (iterates starting from 1).
Cf. also A048727, A269160.

a[n_] := BitXor[4n, BitOr[2n, n]]; Table[a[n], {n, 0, 100}] (* Jean-François Alcover, Feb 23 2016 *)

def A269161(n): return n<<2 ^ (n<<1 |n) # Chai Wah Wu, Jun 29 2022

(define (A269161 n) (A003987bi (* 4 n) (A003986bi (* 2 n) n))) ;; Where A003986bi and A003987bi are implementation of dyadic functions giving bitwise-OR (A003986) and bitwise-XOR (A003987) of their arguments.

a(n) = 4n XOR (2n OR n) = A003987(4*n, A003986(2*n, n)).
a(n) = 4*n XOR A163617(n).
Other identities. For all n >= 0:
a(2*n) = 2*a(n).
a(n) = A057889(A269160(A057889(n))). [Rule 86 is the mirror image of rule 30.]

A213370 a(n) = n AND 2*n, where AND is the bitwise AND operator.

Original entry on oeis.org

0, 0, 0, 2, 0, 0, 4, 6, 0, 0, 0, 2, 8, 8, 12, 14, 0, 0, 0, 2, 0, 0, 4, 6, 16, 16, 16, 18, 24, 24, 28, 30, 0, 0, 0, 2, 0, 0, 4, 6, 0, 0, 0, 2, 8, 8, 12, 14, 32, 32, 32, 34, 32, 32, 36, 38, 48, 48, 48, 50, 56, 56, 60, 62, 0, 0, 0, 2, 0, 0, 4, 6, 0, 0, 0, 2, 8, 8

Offset: 0

Alex Ratushnyak, Jun 14 2012

Antti Karttunen, Table of n, a(n) for n = 0..16384 (terms 0..1023 from T. D. Noe)
Index entries for sequences related to binary expansion of n

Cf. A080099, A213526, A048727, A048735, A269160.
Cf. A003714: indices of 0's.
Cf. A213540: indices of 2's, indices of 4's divided by 2.

Table[BitAnd[n, 2n], {n, 0, 63}] (* Alonso del Arte, Jun 19 2012 *)

a(n) = bitand(n, 2*n); \\ Michel Marcus, Mar 26 2021

for n in range(99):
    print(2*n & n, end=", ")

a(n) = 2 * A048735(n).

a(n) = (1/2)*(A048727(n) XOR A269160(n)) = (n OR 2n) XOR (n XOR 2n). - Antti Karttunen, May 16 2021

A048717 Binary expansion matches ((0)00(1)11)(0).

Original entry on oeis.org

0, 3, 6, 7, 12, 14, 15, 24, 28, 30, 31, 48, 51, 56, 60, 62, 63, 96, 99, 102, 103, 112, 115, 120, 124, 126, 127, 192, 195, 198, 199, 204, 206, 207, 224, 227, 230, 231, 240, 243, 248, 252, 254, 255, 384, 387, 390, 391

Offset: 0

Antti Karttunen, Mar 30 1999

In binary expansion, 1-bits occur only in groups of two or more, separated from other such groups by at least two 0-bits.

Integers that satisfy A048727(n) = 3*n.

Index entries for sequences defined by congruent products between domains N and GF(2)[X]

Row 3 of A115872. Superset of A048719. Cf. A048733.

filterQ[n_] := !MatchQ[IntegerDigits[n, 2], {1}|{1, 0, _}|{_, 0, 1}|{_, 1, 0, 1, _}|{_, 0, 1, 0, _}];
Select[Range[0, 400], filterQ] (* Jean-François Alcover, Dec 31 2020 *)

cp's OEIS Frontend

A048730 Differences between A008589 (multiples of 7) and A048727, a(n) = ((n*7)-Xmult(n,7)).

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A284557 a(n) = A048727(n) mod 3.

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A048720 Multiplication table {0..i} X {0..j} of binary polynomials (polynomials over GF(2)) interpreted as binary vectors, then written in base 10; or, binary multiplication without carries.

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Maple

Mathematica

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A269160 Formula for Wolfram's Rule 30 cellular automaton: a(n) = n XOR (2n OR 4n).

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Mathematica

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A048725 a(n) = Xmult(n,5) or rule90(n,1).

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Maple

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A277320 Square array A(r,c) = A048720(A065621(r), c), read by descending antidiagonals as A(1,1), A(1,2), A(2,1), A(1,3), A(2,2), A(3,1), etc.

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A048715 Binary expansion matches (100(0)*)*(0|1|10)?; or, Zeckendorf-like expansion of n using recurrence f(n) = f(n-1) + f(n-3).

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A048715 Binary expansion matches (100(0))(0|1|10)?; or, Zeckendorf-like expansion of n using recurrence f(n) = f(n-1) + f(n-3).

A048717 Binary expansion matches ((0)00(1)11)(0).