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 1-10 of 21 results. Next

A179762 Binary expansions of A122245 (A122246) concatenated together to a single binary sequence, so that from each term of A122245, the most significant bits come before the least significant bits.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Aug 03 2010

Keywords

Comments

When viewed as a table, the first row contains six terms, the second eight, the third ten, and so on, i.e. row n contains 2(n+2) terms.

Crossrefs

A122246 a(n) = A007088(A122245(n)).

Original entry on oeis.org

101100, 11101000, 1110011000, 111100100100, 11101001011000, 1110110010011000, 111100100110110000, 11110011010001011000, 1110110010010110101000, 111011001110000110110000
Offset: 1

Views

Author

Antti Karttunen, Sep 14 2006

Keywords

Crossrefs

A179776 Quadrisection of the fourth central column of triangle A122245, a(n) = A179775((4*n)-2).

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Aug 03 2010

Keywords

Comments

Conjecture: the last zero (108th) occurs at n=163, after which only ones occur.

Crossrefs

Cf. A179777-A179779, and also A179771, A179831.

Formula

a(n) = A179775((4*n)-2).

A179775 The fourth central column of triangle A122245, i.e., A179762(4), A179762(11), A179762(20), A179762(31), ...

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Aug 03 2010

Keywords

Crossrefs

Cf. A179776-A179779, and also A179770, A179830.

Formula

a(n) = A179762(A028875(n+2)).

A376405 Bitwise XOR (centrally aligned) of two consecutive terms of A122245.

Original entry on oeis.org

176, 584, 2068, 9232, 38952, 135296, 567096, 2444568, 10136288, 34920688, 144732808, 625792608, 2598216176, 8989149792, 37119010736, 160422522664, 665656629200, 2297815400576, 9505629937992, 41066855413976, 169932530966160, 589165636912400, 2439104800321640, 10514745879265952, 43543845360254320, 149771860125187648
Offset: 1

Views

Author

Antti Karttunen, Sep 22 2024

Keywords

Crossrefs

Programs

Formula

a(n) = A122245(1+n) XOR 2*A122245(n).

A376415 a(n) = A122245(4+n) XOR 16*A122245(n).

Original entry on oeis.org

14488, 57880, 258096, 1033752, 3702824, 14821424, 66158736, 264831016, 948570032, 3798139024, 16949183552, 67829237680, 243080889928, 972279514176, 4341071097344, 17360471721544, 62225889019592, 248568875068928, 1111070190653712, 4438793067349704, 15908408008868528, 63634253845942544, 284082756299099488, 1136310075423425200
Offset: 1

Views

Author

Antti Karttunen, Sep 22 2024

Keywords

Comments

This seems to preserve more of the "wavy texture" present in A122245 than what A376412 does vis-a-vis A122242. Compare the corresponding illustrations.

Crossrefs

Programs

A080070 Decimal encoding of parenthesizations produced by simple iteration starting from empty parentheses and where each successive parenthesization is obtained from the previous by reflecting it as a general tree/parenthesization, then adding an extra stem below the root and then reflecting the underlying binary tree.

Original entry on oeis.org

0, 10, 1010, 101100, 10110010, 1011100100, 101100110100, 10111001001100, 1011100110100010, 101110011010011000, 10110011101001100010, 1011110010011011000100, 101100111011010001100100
Offset: 0

Views

Author

Antti Karttunen, Jan 27 2003

Keywords

Comments

Corresponding Lisp/Scheme S-expressions are (), (()), (()()), (()(())), (()(())()), (()((())())), (()(())(()())), ...
Conjecture: only the terms in positions 0,1,2 and 4 are symmetric, i.e., A057164(A080068(n)) = A080068(n) (equivalently: A036044(A080069(n)) = A080069(n)) only when n is one of {0,1,2,4}. If this is true, then the formula given in A079438 is exact. I (AK) have checked this up to n=404631 with no other occurrence of a symmetric (general) tree.

Examples

			This demonstrates how to get the fourth term 10110010 from the 3rd term 101100. The corresponding binary and general trees plus parenthesizations are shown. The first operation reflects the general tree, the second adds a new stem under the root and the third reflects the underlying binary tree, which induces changes on the corresponding general tree:
..............................................
.....\/................\/\/..........\/\/.....
......\/......\/\/......\/............\/......
.....\/........\/........\/..........\/.......
......(A057164).(A057548)..(A057163)..........
........................o.....................
........................|.....................
........o.....o.........o...o.........o.......
........|.....|..........\./..........|.......
....o...o.....o...o.......o.........o.o.o.....
.....\./.......\./........|..........\|/......
......*.........*.........*...........*.......
..[()(())]..[(())()]..[((())())]..[()(())()]..
...101100....110010....11100100....10110010...
		

Crossrefs

Compare to similar Wolframesque plots given in A122229, A122232, A122235, A122239, A122242, A122245. See also A079438, A080067, A080071, A057119.

Formula

a(n) = A007088(A080069(n)) = A063171(A080068(n)).

A122242 a(n) = A014486(A122241(n)).

Original entry on oeis.org

42, 240, 916, 3748, 14960, 62104, 248176, 969304, 3876576, 15962544, 63772488, 248169896, 993554240, 4086635408, 16350541128, 63529835824, 254129143040, 1046249323840, 4184725760584, 16276030608712, 65054467548432, 267635134298624
Offset: 1

Views

Author

Antti Karttunen, Sep 14 2006

Keywords

Comments

Question: to which Wolfram's class does this simple program belong, class 3 or class 4, or is such categorization at all applicable here?

Crossrefs

Cf. A014486, A057548, A082358, A122237, A122241, A122243 (same sequence in binary).
Compare to similar Wolframesque plots given in A080070, A122229, A122232, A122235, A122239, A122245.
Cf. also A376402, A376412.

Programs

  • Python
    # See the Links section

Formula

For n >= 1, a(1+n) = 2*a(n) XOR A376402(n), a(4+n) = 16*a(n) XOR A376412(n). - Antti Karttunen, Sep 23 2024

A080069 a(n) = A014486(A080068(n)).

Original entry on oeis.org

0, 2, 10, 44, 178, 740, 2868, 11852, 47522, 190104, 735842, 3090116, 11777124, 48557252, 194656036, 778669672, 3117617996, 12677727330, 49850271300, 192901051976, 795560529352, 3243898094388, 12977884832332, 51055591319170
Offset: 0

Views

Author

Antti Karttunen, Jan 27 2003

Keywords

Comments

Note that A080068 can be also obtained as iteration of A072795 o A057506.

Crossrefs

Same sequence in binary: A080070. Compare with similar Wolframesque plots given in A122229, A122232, A122235, A122239, A122242, A122245, A328111.
Cf. A179758.

Programs

  • Python
    # See attached program

Extensions

Python program and Wolfram-like plot added by Antti Karttunen, Sep 14 2006

A082358 Permutation of natural numbers: composition of permutations A057163 & A082356.

Original entry on oeis.org

0, 1, 3, 2, 8, 7, 5, 4, 6, 22, 21, 18, 17, 20, 13, 12, 10, 9, 11, 19, 16, 15, 14, 64, 63, 59, 58, 62, 50, 49, 46, 45, 48, 61, 57, 55, 54, 36, 35, 32, 31, 34, 27, 26, 24, 23, 25, 33, 30, 29, 28, 60, 56, 47, 44, 53, 52, 43, 41, 40, 51, 42, 38, 37, 39, 196, 195, 190, 189, 194
Offset: 0

Views

Author

Antti Karttunen, Apr 17 2003

Keywords

Comments

This is the signature-permutation of Catalan automorphism which is derived from nonrecursive Catalan automorphism *A123496 with the recursion schema FORK (defined in A122201). - Antti Karttunen, Oct 11 2006

Crossrefs

Inverse of A082357. Cf. also A082359-A082360.
See the Wolframesque plots of A122242 and A122245.
Row 65796 of table A122201.

Formula

a(n) = A057163(A082356(n))
Showing 1-10 of 21 results. Next