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.

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A080968 Orbit size of each branch-reduced tree encoded by A080981(n) under Donaghey's "Map M" Catalan automorphism.

Original entry on oeis.org

1, 1, 2, 2, 3, 3, 3, 6, 6, 6, 6, 6, 6, 3, 2, 3, 5, 3, 5, 5, 5, 5, 3, 3, 2, 3, 6, 24, 24, 24, 24, 6, 24, 24, 24, 6, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 6, 24, 24, 24, 24, 24, 6, 24, 24, 6, 3, 18, 9, 24, 18, 18, 9, 18, 9, 18, 18, 3, 24, 15, 15, 24, 24, 18, 15, 15, 24, 3, 24, 24, 15, 15, 24
Offset: 0

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Author

Antti Karttunen, Mar 02 2003

Keywords

Comments

This is the size of the cycle containing A080980(n) in the permutations A057505/A057506.
If the conjecture given in A080070 is true, then this sequence contains only six 2's. Questions: are there any (other) values with finite number of occurrences? Which primes will eventually appear?

Crossrefs

Formula

a(n) = A080967(A080980(n))

A126312 Fixed points of permutation A071661/A071662.

Original entry on oeis.org

0, 1, 2, 3, 4, 8, 9, 22, 23, 30, 55, 64, 65, 98, 158, 196, 197, 318, 484, 625, 626, 687, 1042, 1549, 1973, 2055, 2056, 2376, 3471, 5113, 6558, 6917, 6918, 8191, 11763, 17268, 22277, 23713, 23714, 24331, 28360, 40491, 59362, 76942, 81754, 82499
Offset: 0

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Author

Antti Karttunen, Jan 16 2007

Keywords

Comments

Those i for which A071661(i)=i, i.e. for which A057163(A057164(i)) = A057164(A057163(i)). These appear to consist of just those general plane trees which are symmetric and will stay symmetric also after the underlying plane binary tree has been reflected, i.e. for which A057164(i)=i and A057164(A057163(i)) = A057163(i). See comments at A123050 and A080070. The sequence seems to give also the fixed points of the permutation A125977/A125978.

A154473 a(n) = A014486(A154472(n)).

Original entry on oeis.org

842, 11090, 13202, 46882, 60994, 231272004, 198873570440, 266349291297936, 64442911458703648, 3667589230123774528, 3336154829743802737792, 17601566387699271821281536, 1023499990310357893964861952
Offset: 0

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Author

Antti Karttunen, with terms a(0)-a(100) also independently computed by Wouter Meeussen, with the given Mathematica program, Jan 11 2009

Keywords

Comments

This sequence gives the parenthesis expressions shown at the upper right corner image of the page 103 of NKS, with the left brackets (black squares) converted to 1's and the right brackets (white squares) converted to 0's and then interpreting each such number as a binary number and converted to decimal. A154474 shows the corresponding binary representations. Compare to A080070, A122242, A122245.

Crossrefs

Programs

  • Mathematica
    init=e[e[e][e]][e][e]
    toDeca[ w_ ]:=FromDigits[ ToExpression[ Characters[ ToString[ w ] ]/.{"e"->Sequence[], "["->"1","]"->"0"} ],2 ]
    toDeca /@ NestList[ #/.e[x_ ][y_ ]->x[x[y]]&, init, 100]

A154477 a(n) = A153240(A080068(n)).

Original entry on oeis.org

0, 0, 0, 1, 0, 3, 2, 0, 1, 7, 4, 9, 8, 6, 7, 5, -6, -10, 16, 15, 10, -11, -15, 16, 22, 19, 24, 23, 18, 14, 28, 25, 21, 23, 11, -7, -26, 35, 34, 29, -18, 39, 38, 9, -8, 38, 33, -31, -35, 42, 37, 31, 32, 51, 48, -46, 54, 51, 40, -43, 58, 55, 43, 61, 60, 58, 52, 65, 62, -2, 68
Offset: 0

Views

Author

Antti Karttunen, Jan 11 2009

Keywords

Comments

This sequence gives some indication of how well the terms of A080068 are balanced as general trees, which has some implications as to the correctness of A123050 (see comments at A080070).

Crossrefs

See also A080071.

A179417 a(n) is the binary number (shown here in decimal) constructed from quadratic residues of 65537 in range [(n^2)+1,(n+1)^2] in such a way that quadratic residues are mapped to 1-bits, and non-quadratic residues (as well as the multiples of 65537) to 0-bits, with the lower end of range mapped to less significant, and the higher end of range to more significant bits.

Original entry on oeis.org

1, 5, 24, 104, 279, 2001, 4131, 17453, 88826, 362532, 1655660, 6120642, 25376649, 128526482, 301370205, 1756488602, 8046359747, 30854867177, 73845140753, 488906501177, 2106640948770, 6573967883049, 29711211505300
Offset: 0

Views

Author

Antti Karttunen, Jul 27 2010

Keywords

Comments

The binary width of terms are 1, 3, 5, 7, 9, ... i.e., the successive odd numbers, as their partial sums give the squares, 1, 4, 9, 16, ... at which points there certainly is always a quadratic residue, which thus gives the most significant bit for each number.

Examples

			In the range [(2^2)+1, (2+1)^2] (i.e., [5,9]) we have A165471(5)=A165471(6)=A165471(7)=-1 and A165471(8)=A165471(9)=+1, i.e., there are quadratic non-residues at points 5, 6 and 7, and quadratic residues at 8 and 9, so we construct a binary number 11000, which is 24 in decimal, thus a(2)=24.
		

Crossrefs

Cf. A179418.
Compare to similar bit triangle illustrations given in A080070, A122229, A122232, A122235, A122239, A122242, A122245.

A328111 a(n) = A080069(n) OR A267357(n).

Original entry on oeis.org

1, 3, 15, 47, 191, 743, 2935, 12015, 47615, 190363, 737255, 3092431, 11777535, 48562151, 194672615, 778681963, 3117668351, 12677730147, 49850341191, 192901085003, 795560607711, 3243899871031, 12977889600367, 51055599708139, 204124618746111, 791262494980483, 3318011560984519, 12661179187462123, 52138250822737375, 212591566440951715, 836346216751952367, 3236342451194541807
Offset: 0

Views

Author

Antti Karttunen, Oct 05 2019

Keywords

Comments

The pattern has a remarkably nice texture. A269174 gives the trajectory of 1-D Cellular Automaton rule 124 (which is a mirror image of rule 110), when started from a single alive cell. Trails of its evolution can be dimly discerned on the right hand side of given illustrations, while the left hand side shows the evolution of (left hand side of) iterated Dyck-path system A080069 unblemished.

Crossrefs

Cf. A080069, A080070, and also A079438 and A123050.
Cf. also A328103.

Formula

a(n) = A080069(n) OR A267357(n), where OR is bitwise-OR, A003986.

A154474 a(n) = A007088(A154473(n)).

Original entry on oeis.org

1101001010, 10101101010010, 11001110010010, 1011011100100010, 1110111001000010, 1101110010001110111001000100, 10111001001101110010011101110010001000
Offset: 0

Views

Author

Antti Karttunen, Jan 11 2009

Keywords

Comments

This sequence gives the parenthesis expressions shown at the upper right corner image of the page 103 of NKS, with left brackets (black squares) converted to 1's and right brackets (white squares) converted to 0's. Compare to A080070, A122242, A122245.
Previous Showing 21-27 of 27 results.