cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-6 of 6 results.

A322408 Compound sequence with a(n) = A319198(A278041(n)), for n >= 0.

Original entry on oeis.org

3, 7, 11, 15, 18, 22, 26, 30, 34, 38, 42, 45, 49, 53, 57, 61, 65, 68, 72, 76, 80, 84, 88, 92, 95, 99, 103, 107, 110, 114, 118, 122, 126, 130, 134, 137, 141, 145, 149, 153, 157, 160, 164, 168, 172, 176, 180, 184, 187, 191, 195, 199, 203, 207, 211, 214, 218, 222, 226, 230, 234
Offset: 0

Views

Author

Wolfdieter Lang, Jan 02 2019

Keywords

Comments

Old name was: Compound tribonacci sequence a(n) = A319198(A278041(n)), for n >= 0.
a(n) gives the sum of the entries of the tribonacci word sequence t = A080843 not exceeding t(C(n)), with C(n) = A278041(n).
The nine sequences A308199, A319967, A319968, A322410, A322409, A322411, A322413, A322412, A322414 are based on defining the tribonacci ternary word to start with index 0 (in contrast to the usual definition, in A080843 and A092782, which starts with index 1). As a result these nine sequences differ from the compound tribonacci sequences defined in A278040, A278041, and A319966-A319972. - N. J. A. Sloane, Apr 05 2019
The difference sequence (a(n+1)-a(n)) is equal to a change of alphabet of the tribonacci word t = A092782. The alphabet is {4,4,3}. This follows from the formula a(n) = A278039(n) + 2*n + 3. - Michel Dekking, Oct 05 2019

Examples

			n = 2: C(2) = 16, t = {0, 1, 0, 2, 0, 1, 0, 0, 1, 0, 2, 0, 1, 0, 1, 0, 2, ...} which sums to 11 = a(2) = 4 + 7, because B(2) = 4.
		

Crossrefs

Formula

a(n) = z(C(n)) = Sum_{j=0..C(n)} t(j), n >= 0, with z = A319198, C = A278041 and t = A080843.
a(n) = B(n) + 2*n + 3, where B(n) = A278039(n). For a proof see the W. Lang link in A080843, Proposition 8, eq. (47).
a(n) = 3 + Sum_{k=1..n-1} d(k), where d is the tribonacci sequence on the alphabet {4,4,3}. - Michel Dekking, Oct 05 2019

Extensions

Name changed by Michel Dekking, Oct 08 2019

A321333 Compound sequence with a(n) = A319198(A278040(n)), for n >= 0.

Original entry on oeis.org

1, 4, 5, 8, 9, 12, 13, 16, 19, 20, 23, 24, 27, 28, 31, 32, 35, 36, 39, 40, 43, 46, 47, 50, 51, 54, 55, 58, 59, 62, 63, 66, 69, 70, 73, 74, 77, 78, 81, 82, 85, 86, 89, 90, 93, 96, 97, 100, 101, 104, 105, 108, 111, 112, 115, 116, 119, 120, 123, 124, 127
Offset: 0

Views

Author

Wolfdieter Lang, Dec 27 2018

Keywords

Comments

Old name was: Compound tribonacci sequence a(n) = A319198(A278040(n)), for n >= 0.
a(n) gives the sum of the entries of the tribonacci word sequence t = A080843 not exceeding t(A(n)), with A(n) = A278040(n).

Examples

			n = 4, A(4) = 14, t = {0, 1, 0, 2, 0, 1, 0, 0, 1, 0, 2, 0, 1, 0, 1, ...}, which sums to  9  = a(4) = 2*(14 - 7) - 5, because B(4) = 7.
		

Crossrefs

Formula

a(n) = z(A(n)) = Sum_{j=0..A(n)} t(j), n >= 0, with z = A319198, A = A278040 and t = A080843.
a(n) = 2*(A(n) - B(n)) - (n + 1), where B(n) = A278039(n). For a proof see the W. Lang link in A080843, Proposition 8, eq. (45).
a(n)= 1 + Sum_{k=1..n-1} d(k), where d is the tribonacci sequence on the alphabet {3,1,1}. - Michel Dekking, Oct 08 2019

Extensions

Name changed by Michel Dekking, Oct 08 2019

A322407 Compound sequence a(n) = A319198(A278039(n)), for n >= 0.

Original entry on oeis.org

0, 1, 3, 4, 4, 5, 7, 8, 9, 11, 12, 12, 13, 15, 16, 18, 19, 19, 20, 22, 23, 24, 26, 27, 27, 28, 30, 31, 31, 32, 34, 35, 36, 38, 39, 39, 40, 42, 43, 45, 46, 46, 47, 49, 50, 51, 53, 54, 54, 55, 57, 58, 59, 61, 62, 62, 63, 65, 66, 68, 69
Offset: 0

Views

Author

Wolfdieter Lang, Jan 02 2019

Keywords

Comments

Old name was: Compound tribonacci sequence a(n) = A319198(A278039(n)), for n >= 0.
a(n) gives the sum of the entries of the tribonacci word sequence t = A080843 not exceeding t(B(n)), with B(n) = A278039(n).

Examples

			n = 3: B(3) = 6, t = {0, 1, 0, 2, 0, 1, 0, ...} which sums to 4 = a(3) = -12 + 3*6 - 2, because A(3) = 12.
		

Crossrefs

Formula

a(n) = z(B(n)) = Sum_{j=0..B(n)} t(j), n >= 0, with z = A319198, B = A278039 and t = A080843.
a(n) = -A(n) + 3*B(n) - (n - 1), where A(n) = A278040(n). For a proof see the W. Lang link in A080843, Proposition 8, eq. (46).
a(n) = Sum_{k=1..n-1} d(k), where d is the tribonacci sequence on the alphabet {1,2,0}. - Michel Dekking, Oct 08 2019

Extensions

Name changed by Michel Dekking, Oct 07 2019

A080843 Tribonacci word: limit S(infinity), where S(0) = 0, S(1) = 0,1, S(2) = 0,1,0,2 and for n >= 0, S(n+3) = S(n+2) S(n+1) S(n).

Original entry on oeis.org

0, 1, 0, 2, 0, 1, 0, 0, 1, 0, 2, 0, 1, 0, 1, 0, 2, 0, 1, 0, 0, 1, 0, 2, 0, 1, 0, 2, 0, 1, 0, 0, 1, 0, 2, 0, 1, 0, 1, 0, 2, 0, 1, 0, 0, 1, 0, 2, 0, 1, 0, 0, 1, 0, 2, 0, 1, 0, 1, 0, 2, 0, 1, 0, 0, 1, 0, 2, 0, 1, 0, 2, 0, 1, 0, 0, 1, 0, 2, 0, 1, 0, 1, 0, 2, 0, 1, 0, 0, 1, 0, 2, 0, 1, 0, 1, 0, 2, 0, 1, 0, 0, 1, 0, 2
Offset: 0

Views

Author

N. J. A. Sloane, Mar 29 2003

Keywords

Comments

An Arnoux-Rauzy or episturmian word.
From N. J. A. Sloane, Jul 10 2018: (Start)
The initial terms in a form suitable for copying:
0,1,0,2,0,1,0,0,1,0,2,0,1,0,1,0,2,0,1,0,0,1,0,2,0,1,0,2,0,1,0,0,1,0,2,0,1,
0,1,0,2,0,1,0,0,1,0,2,0,1,0,0,1,0,2,0,1,0,1,0,2,0,1,0,0,1,0,2,0,1,0,2,0,1,
0,0,1,0,2,0,1,0,1,0,2,0,1,0,0,1,0,2,0,1,0,1,0,2,0,1,0,0,1,0,2,0,1,0,2,0,1,
0,0,1,0,2,0,1,0,1,0,2,0,1,0,0,1,0,2,0,1,0,0,1,0,2,0,1,0,1,0,2,0,1,0,0,1,0,
2,0,1,0,2,0,1,0,0,1,0,2,0,1,0,1,0,2,0,1,0,0,1,0,2,0,1,0,2,0,1,0,0,1,0,2,0,
1,0,1,0,2,0,1,0,0,1,0,2,0,1,0,0,1,0,2,0,1,0,1,0,2,0,1,0,0,1,0,2,0,1,0,2,0,
1,0,0,1,0,2,0,1,0,1,0,2,0,1,0,0,1,0,2,0,1,0,1,0,2,0,1,0,0,1,0,2,0,1,0,2,0,
1,0,0,1,0,2,0,1,0,1,0,2,0,1,0,0,1,0,2,0,1,0,0,1,0,2,0,1,0,1,0,2,0,1,0,0,1,
...
Let TTW(a,b,c) denote this sequence written over the alphabet {a,b,c}. It begins:
a,b,a,c,a,b,a,a,b,a,c,a,b,a,b,a,c,a,b,a,a,b,a,c,a,b,a,c,a,b,a,a,b,a,c,a,b,
a,b,a,c,a,b,a,a,b,a,c,a,b,a,a,b,a,c,a,b,a,b,a,c,a,b,a,a,b,a,c,a,b,a,c,a,b,
a,a,b,a,c,a,b,a,b,a,c,a,b,a,a,b,a,c,a,b,a,b,a,c,a,b,a,a,b,a,c,a,b,a,c,a,b,
a,a,b,a,c,a,b,a,b,a,c,a,b,a,a,b,a,c,a,b,a,a,b,a,c,a,b,a,b,a,c,a,b,a,a,b,a,
c,a,b,a,c,a,b,a,a,b,a,c,a,b,a,b,a,c,a,b,a,a,b,a,c,a,b,a,c,a,b,a,a,b,a,c,a,
b,a,b,a,c,a,b,a,a,b,a,c,a,b,a,a,b,a,c,a,b,a,b,a,c,a,b,a,a,b,a,c,a,b,a,c,a,
b,a,a,b,a,c,a,b,a,b,a,c,a,b,a,a,b,a,c,a,b,a,b,a,c,a,b,a,a,b,a,c,a,b,a,c,a,
b,a,a,b,a,c,a,b,a,b,a,c,a,b,a,a,b,a,c,a,b,a,a,b,a,c,a,b,a,b,a,c,a,b,a,a,b,
... (End)
From Wolfdieter Lang, Aug 14 2018: (Start)
The substitution sequence 0 -> 0, 1; 1-> 0, 2; 2 -> 0 read as an irregular triangle with rows l >= 1 and length T(l+2), with the tribonacci numbers T = A000073, leads to the tribonacci tree TriT with level TriT(l) for l >= 1 given by a(0), a(1), ..., a(T(l+2)-1).
E.g., l = 4: 0 1 0 2 0 1 0 with T(6) = 7 leaves (nodes). See the example below.
This tree can be used to find the tribonacci representation of nonnegative n given in A278038, call it ZTri(n) (Z for generalized Zeckendorf), by replacing every 2 by 1, and reading from bottom to top, omitting the final 0, except for n = 0 which is represented by 0. See the example below. (End)

Examples

			From _Joerg Arndt_, Mar 12 2013: (Start)
The first few steps of the substitution are
Start: 0
Rules:
  0 --> 01
  1 --> 02
  2 --> 0
-------------
0:   (#=1)
  0
1:   (#=2)
  01
2:   (#=4)
  0102
3:   (#=7)
  0102010
4:   (#=13)
  0102010010201
5:   (#=24)
  010201001020101020100102
6:   (#=44)
  01020100102010102010010201020100102010102010
7:   (#=81)
  010201001020101020100102010201001020101020100102010010201010201001020102010010201
(End)
From _Wolfdieter Lang_, Aug 14 2018: (Start)
The levels l of the tree TriT begin (the branches (edges) have been omitted):
Substitution rule: 0 -> 0 1; 1 -> 0 2; 2 -> 0.
l=1:                                 0
l=2:                  0                                 1
l=3:             0             1                  0             2
l=4:         0      1       0     2          0       1          0
l=5:      0    1  0   2   0   1   0        0   1   0   2      0    1
...
----------------------------------------------------------------------------------
n =       0    1  2   3   4   5   6        7   8   9  10     11   12
The tribonacci representation of n >= 0 (A278038; here at level 5 for n = 0.. 12) is obtained by reading from bottom to top (along the branches not shown) replacing 2 with 1, omitting the last 0 except for n = 0.
          0    1  0   1   0   1   0        0   1   0  1      0    1
                  1   1   0   0   1        0   0   1  1      0    0
                          1   1   1        0   0   0  0      1    1
                                           1   1   1  1      1    1
E.g., ZTri(9) = A278038(9) = 1010. (End)
		

References

  • The entry A092782 has a more complete list of references and links. - N. J. A. Sloane, Aug 17 2018
  • J.-P. Allouche and J. Shallit, Automatic Sequences, Cambridge Univ. Press, 2003, p. 246.

Crossrefs

Cf. A003849 (the Fibonacci word), A092782.
See A092782 for a version over the alphabet {1,2,3}.
See A278045 for another construction.
First differences: A317950. Partial sums: A319198.

Programs

  • Maple
    M:=17; S[1]:=`0`; S[2]:=`01`; S[3]:=`0102`;
    for n from 4 to M do S[n]:=cat(S[n-1], S[n-2], S[n-3]); od:
    t0:=S[M]: l:=length(t0); for i from 1 to l do lprint(i,substring(t0,i..i)); od:
    # N. J. A. Sloane, Nov 01 2006
    # A version that uses the letters a,b,c:
    M:=10; B[1]:=`a`; B[2]:=`ab`; B[3]:=`abac`;
    for n from 4 to M do B[n]:=cat(B[n-1], B[n-2], B[n-3]); od:
    B[10]; # N. J. A. Sloane, Oct 30 2018
  • Mathematica
    Nest[Flatten[ # /. {0 -> {0, 1}, 1 -> {0, 2}, 2 -> {0}}] &, {0}, 8] (* updated by Robert G. Wilson v, Nov 07 2010 *)
    SubstitutionSystem[{0->{0,1},1->{0,2},2->{0}},{0},{8}]//Flatten (* Harvey P. Dale, Nov 21 2021 *)
  • PARI
    strsub(s, vv, off=0)=
    {
        my( nl=#vv, r=[], ct=1 );
        while ( ct <= #s,
            r = concat(r, vv[ s[ct] + (1-off) ] );
            ct += 1;
        );
        return( r );
    }
    t=[0];  for (k=1, 10, t=strsub( t, [[0,1], [0,2], [0]], 0 ) );  t
    \\ Joerg Arndt, Sep 14 2013

Formula

Fixed point of morphism 0 -> 0, 1; 1 -> 0, 2; 2 -> 0.
a(n) = A092782(n+1) - 1. - Joerg Arndt, Sep 14 2013

Extensions

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 06 2003

A278040 The tribonacci representation of a(n) is obtained by appending 0,1 to the tribonacci representation of n (cf. A278038).

Original entry on oeis.org

1, 5, 8, 12, 14, 18, 21, 25, 29, 32, 36, 38, 42, 45, 49, 52, 56, 58, 62, 65, 69, 73, 76, 80, 82, 86, 89, 93, 95, 99, 102, 106, 110, 113, 117, 119, 123, 126, 130, 133, 137, 139, 143, 146, 150, 154, 157, 161, 163, 167, 170, 174, 178, 181, 185, 187, 191, 194, 198, 201, 205, 207, 211, 214, 218, 222, 225, 229, 231, 235
Offset: 0

Views

Author

N. J. A. Sloane, Nov 18 2016

Keywords

Comments

This sequence gives the A(n) numbers of the W. Lang link. There the B(n) and C(n) numbers are A278039(n) and A278041(n), respectively. - Wolfdieter Lang, Dec 05 2018
Positions of letter b in the tribonacci word t generated by a->ab, b->ac, c->a, when given offset 0. - Michel Dekking, Apr 03 2019
This sequence gives the positions of the word ab in the tribonacci word t. This follows from the fact that the letter b is always preceded in t by the letter a, and the formula AA = B-1, where A := A003144, B := A003145, C := A003146. - Michel Dekking, Apr 09 2019

Examples

			The tribonacci representation of 7 is 1000 (see A278038), so a(7) has tribonacci representation 100001, which is 24+1 = 25, so a(7) = 25.
		

Crossrefs

By analogy with the Wythoff compound sequences A003622 etc., the nine compounds of A003144, A003145, A003146 might be called the tribonacci compound sequences. They are A278040, A278041, and A319966-A319972.

Formula

a(n) = A003145(n+1) - 1.
a(n) = A003144(A003144(n)). - N. J. A. Sloane, Oct 05 2018
See Theorem 13 in the Carlitz, Scoville and Hoggatt paper. - Michel Dekking, Mar 20 2019
From Wolfdieter Lang, Dec 13 2018: (Start)
This sequence gives the indices k with A080843(k) = 1, ordered increasingly with offset 0.
a(n) = 1 + 4*n - A319198(n-1), n >= 0, with A319198(-1) = 0.
a(n) = A276796(C(n)) - 1, with C(n) = A278041(n).
For a proof see the W. Lang link, Proposition 5, and eq. (58).
a(n) - 1 = B1(n), where B1-numbers are B-numbers from A278039 followed by an A-number from A278040. See a comment and example in A319968.
a(n) - 1 = B(B(n)) = B(B(n) + 1) - 2, for n > = 0, where B = A278039.
(End)

A324470 Partial sums of ternary tribonacci word A092782.

Original entry on oeis.org

1, 3, 4, 7, 8, 10, 11, 12, 14, 15, 18, 19, 21, 22, 24, 25, 28, 29, 31, 32, 33, 35, 36, 39, 40, 42, 43, 46, 47, 49, 50, 51, 53, 54, 57, 58, 60, 61, 63, 64, 67, 68, 70, 71, 72, 74, 75, 78, 79, 81, 82, 83, 85, 86, 89, 90, 92, 93, 95, 96, 99, 100, 102, 103
Offset: 1

Views

Author

N. J. A. Sloane, Mar 03 2019

Keywords

Crossrefs

Showing 1-6 of 6 results.