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 1-3 of 3 results.

A072764 Tabular N X N -> N bijection induced by Lisp/Scheme function 'cons' combining the two planar binary trees/general trees/parenthesizations encoded by A014486(X) and A014486(Y).

Original entry on oeis.org

0, 1, 3, 2, 7, 6, 4, 8, 16, 14, 5, 17, 19, 42, 15, 9, 18, 44, 51, 43, 37, 10, 20, 47, 126, 52, 121, 38, 11, 21, 53, 135, 127, 149, 122, 39, 12, 22, 56, 154, 136, 385, 150, 123, 40, 13, 45, 60, 163, 155, 413, 386, 151, 124, 41, 23, 46, 128, 177, 164, 475, 414, 387, 152
Offset: 0

Views

Author

Antti Karttunen Jun 12 2002

Keywords

Crossrefs

Inverse permutation: A072765. a(n) = A069770(A072766(n)). Also transpose of A072766, i.e. a(n) = A072766(A038722(n)). The upper triangular region: A072773. Projection functions are A072771 ('car') & A072772 ('cdr'). The sizes of the corresponding Catalan structures: A072768. The first row: A057548, the first column: A072795, diagonal: A083938. Cf. also A080300, A025581, A002262.

Extensions

a(0)=0 prepended by Sean A. Irvine, Oct 25 2024

A083940 A014486-indices of symmetric binary trees.

Original entry on oeis.org

0, 1, 6, 43, 51, 389, 416, 477, 504, 551, 4102, 4191, 4397, 4485, 4649, 5100, 5187, 5393, 5481, 5645, 5964, 6051, 6215, 6489, 47404, 47700, 48403, 48697, 49268, 50833, 51126, 51828, 52120, 52691, 53829, 54120, 54690, 55690, 59334, 59627, 60328
Offset: 0

Views

Author

Antti Karttunen, May 13 2003

Keywords

Comments

Fixed points of permutation A057163.

Crossrefs

a(n) = A080300(A083941(n)). Cf. A083938, A084108.

Formula

a(0)=0, a(n)=A072764bi(n-1, A057163(n-1)).

A083939 A014486-encoding of binary trees whose left and right subtree are identical.

Original entry on oeis.org

0, 2, 50, 842, 908, 13610, 13868, 14642, 14900, 15416, 218282, 219308, 222386, 223412, 225464, 234698, 235724, 238802, 239828, 241880, 247010, 248036, 250088, 254192, 3494570, 3498668, 3510962, 3515060, 3523256, 3560138, 3564236, 3576530
Offset: 0

Views

Author

Antti Karttunen, May 13 2003

Keywords

Formula

a(n) = A014486(A083938(n)).
Showing 1-3 of 3 results.