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 23 results. Next

A179761 Binary expansions of A122242 (A122243) concatenated together to a single binary sequence, so that from each term of A122242, the most significant bits come before the least significant bits.

Original entry on oeis.org

1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 1, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 1, 1, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 0, 1, 1, 0, 0, 1, 0, 1, 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

A122243 a(n) = A007088(A122242(n)).

Original entry on oeis.org

101010, 11110000, 1110010100, 111010100100, 11101001110000, 1111001010011000, 111100100101110000, 11101100101001011000, 1110110010011011100000, 111100111001000110110000
Offset: 1

Views

Author

Antti Karttunen, Sep 14 2006

Keywords

Crossrefs

A179771 Quadrisection of the fourth central column of triangle A122242, a(n) = A179770(4*n).

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Aug 03 2010

Keywords

Comments

Conjecture: the last zero (107th) occurs at n=166, after which only ones occur.

Crossrefs

Cf. A179772-A179774, and also A179776, A179831.

Formula

a(n) = A179770(4*n).

A179831 Quadrisection of the fourth central column of triangle A122242, a(n) = A179830((4*n)+1).

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Aug 03 2010

Keywords

Comments

Conjecture: the last zero (119th) occurs at n=164, after which only ones occur.

Crossrefs

Cf. A179832-A179834, and also A179771, A179776.

Formula

a(n) = A179830((4*n)+1).

A179770 The fourth central column of triangle A122242, i.e., A179761(4), A179761(11), A179761(20), A179761(31), ...

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Aug 03 2010

Keywords

Crossrefs

Cf. A179771-A179774, and also A179775, A179830.

Formula

a(n) = A179761(A028875(n+2)).

A376402 Bitwise XOR (centrally aligned) of two consecutive terms of A122242.

Original entry on oeis.org

164, 628, 2444, 10040, 34424, 142400, 612536, 2536016, 8772720, 36320296, 156298040, 648930320, 2246427920, 9290072680, 40123676576, 166398412640, 574717970240, 2376856817864, 10244120543704, 42544644116352, 146496800436256, 607708669110320, 2625008220416552, 10882360875506928, 37586414897168848, 156056124134144296
Offset: 1

Views

Author

Antti Karttunen, Sep 22 2024

Keywords

Crossrefs

Programs

Formula

a(n) = A122242(1+n) XOR 2*A122242(n).

A376412 a(n) = A122242(4+n) XOR 16*A122242(n).

Original entry on oeis.org

14544, 64920, 258096, 925720, 3703264, 16562224, 66158664, 237396008, 948568384, 4239130768, 16949182920, 60767078320, 243080890624, 1085016114240, 4341071150792, 15535530051144, 62225888982288, 277421534227968, 1111070191401136, 3979658311943880, 15908408006551904, 71162952082313488, 284082756324759560, 1019946695587234480
Offset: 1

Views

Author

Antti Karttunen, Sep 22 2024

Keywords

Comments

See comments in A376415.

Crossrefs

Programs

Formula

a(n) = A122242(4+n) XOR 16*A122242(n).

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)).

A122245 a(n) = A014486(A122244(n)).

Original entry on oeis.org

44, 232, 920, 3876, 14936, 60568, 248240, 996440, 3876264, 15524272, 63773584, 255477160, 993549616, 3970767760, 16350559552, 65386339632, 254129067336, 1016476056896, 4184726043136, 16740063237448, 65054466609736, 260416091191808
Offset: 1

Views

Author

Antti Karttunen, Sep 14 2006

Keywords

Comments

Questions: to which Wolfram's class does this simple program belong, class 3 or class 4? (Is that classification applicable here? This is not 1D CA, although it may look like one).
Does the "central skyscraper" continue widening forever? (see the image for up to 16384th generation) At what specific points it widens? (A new sequence for that). How does that differ from A122242 and similar sister sequences, with different starting conditions?
Related comments in A179777.

Crossrefs

A122246 shows the same sequence in binary. Compare to similar Wolframesque plots given in A080070, A122229, A122232, A122235, A122239, A122242, A179755, A179757. Cf. also A179777, A179762, A179417.

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
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