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.

Previous Showing 31-39 of 39 results.

A057517 Binary encodings of the Catalan mountain ranges with exactly one sea-level valley, i.e., the rooted plane trees with root degree = 2.

Original entry on oeis.org

10, 44, 50, 180, 184, 204, 210, 226, 724, 728, 740, 744, 752, 820, 824, 844, 850, 866, 908, 914, 930, 962, 2900, 2904, 2916, 2920, 2928, 2964, 2968, 2980, 2984, 2992, 3012, 3016, 3024, 3040, 3284, 3288, 3300, 3304, 3312, 3380, 3384, 3404, 3410, 3426
Offset: 1

Views

Author

Antti Karttunen, Sep 03 2000

Keywords

Comments

This bijective mapping from all rooted plane trees to one node larger, root degree = 2 trees illustrates the fact that CONV(A000108, A000108) = LEFT(A000108). (Catalan numbers shift left under convolution).

Crossrefs

Cf. A057501 (for binexp2pars, pars2binexp, car, cdr), A057518, A057519, A057122. Single-trunked trees: A057547.

Programs

  • Maple
    alltrees2doubletrunked := n -> pars2binexp(alltrees2doubletrunkedP(binexp2pars(n)));
    alltrees2doubletrunkedP := h -> [car(h),cdr(h)];

Formula

a(n) = alltrees2doubletrunked(A014486(n)) (Starting from n=1).

A057547 A014486-encodings of Catalan mountain ranges with no sea-level valleys, i.e., the rooted plane general trees with root degree = 1.

Original entry on oeis.org

2, 12, 52, 56, 212, 216, 228, 232, 240, 852, 856, 868, 872, 880, 916, 920, 932, 936, 944, 964, 968, 976, 992, 3412, 3416, 3428, 3432, 3440, 3476, 3480, 3492, 3496, 3504, 3524, 3528, 3536, 3552, 3668, 3672, 3684, 3688, 3696, 3732, 3736, 3748, 3752, 3760
Offset: 0

Views

Author

Antti Karttunen Sep 07 2000

Keywords

Comments

This one-to-one correspondence between all rooted plane trees and one node larger, root degree = 1 trees illustrates the fact that INVERT(A000108) = LEFT(A000108). (Catalan numbers shift left under Cameron's A transformation.)
From Ruud H.G. van Tol, May 13 2024: (Start)
Sequence on a lattice:
Tree Paths Decimal Count
|_ 10 2 1
|. 1100 12 1
||._ 110100 -111000 52,56 2
|||_._ 11010100 -11110000 212-240 5
|||_|. 1101010100-1111100000 852-992 14
... (End)

Crossrefs

Double-trunked trees: A057517. Cf. also A057548, A057549.

Programs

  • Maple
    alltrees2singletrunked := n -> pars2binexp([binexp2pars(n)]); # Just surround with extra parentheses.
  • PARI
    a_rows(N) = my(a=Vec([[2]], N)); for(r=1, N-1, my(b=a[r], c=List()); foreach(b, t, for(i=1, valuation(t, 2), listput(~c, (t<<2)+(2<Ruud H.G. van Tol, May 25 2024

Formula

a(n) = A014486(A057548(n)) and also from n > 0 onward = A079946(A014486(n)).
a(n) = alltrees2singletrunked(A014486[n]) (see Maple code below and in A057501).

A069889 Self-inverse permutation of natural numbers induced by the automorphism RotateHandshakes_et_DeepReverse! acting on the parenthesizations encoded by A014486.

Original entry on oeis.org

0, 1, 3, 2, 7, 8, 6, 4, 5, 17, 20, 18, 21, 22, 16, 19, 14, 9, 11, 15, 10, 12, 13, 45, 54, 48, 57, 61, 46, 55, 49, 58, 62, 50, 59, 63, 64, 44, 53, 47, 56, 60, 42, 51, 37, 23, 28, 39, 25, 30, 33, 43, 52, 38, 24, 29, 40, 26, 31, 34, 41, 27, 32, 35, 36, 129, 157, 138, 166, 180
Offset: 0

Views

Author

Antti Karttunen, Apr 16 2002

Keywords

Comments

This automorphism reflects non-crossing handshakes (the interpretation n of Stanley's exercise 19) over the diagonal that goes through corner at "11 o'clock".

Crossrefs

Composition of A057501 and A057164, i.e. A069888(n) = A057164(A057501(n)). Cf. also A069888.

A085173 Permutation of natural numbers induced by the Catalan bijection gma085173 acting on symbolless S-expressions encoded by A014486/A063171.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Jun 23 2003

Keywords

Comments

This Catalan bijection rotates by "half step" the interpretations (pp)-(rr) of Stanley, using the "rising slope" mapping illustrated in A085161.

Crossrefs

Inverse: A085174. a(n) = A085161(A085174(A085161(n))) = A085169(A057501(A085170(n))) = A074684(A057501(A074683(n))). Occurs in A073200. Cf. also A085159 (whole step rotate), A086427.
Number of cycles: A002995. Number of fixed points: A019590. Max. cycle size: A057543. (In range [A014137(n-1)..A014138(n-1)] of this permutation, possibly shifted one term left or right).

A123501 Signature permutation of a Catalan automorphism: apply *A123497 at the root, then recurse into the left subtree of the right hand side subtree of a binary tree.

Original entry on oeis.org

0, 1, 2, 3, 4, 6, 7, 5, 8, 9, 10, 14, 16, 19, 17, 18, 12, 11, 13, 20, 15, 21, 22, 23, 24, 25, 26, 27, 37, 38, 42, 44, 47, 51, 53, 56, 60, 45, 46, 48, 49, 50, 31, 34, 30, 28, 29, 35, 33, 32, 36, 54, 55, 40, 39, 41, 57, 43, 58, 59, 61, 52, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71
Offset: 0

Views

Author

Antti Karttunen, Oct 11 2006

Keywords

Crossrefs

Inverse: A123502. A057501(n) = A083927(a(A057123(n))) = A083927(A085159(A057123(n))).

A215406 A ranking algorithm for the lexicographic ordering of the Catalan families.

Original entry on oeis.org

0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 3, 3, 3, 3, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 5, 5, 5, 5, 5, 5, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4
Offset: 0

Views

Author

Peter Luschny, Aug 09 2012

Keywords

Comments

See Antti Karttunen's code in A057117. Karttunen writes: "Maple procedure CatalanRank is adapted from the algorithm 3.23 of the CAGES (Kreher and Stinson) book."
For all n>0, a(A014486(n)) = n = A080300(A014486(n)). The sequence A080300 differs from this one in that it gives 0 for those n which are not found in A014486. - Antti Karttunen, Aug 10 2012

Crossrefs

Programs

  • Maple
    A215406 := proc(n) local m,a,y,t,x,u,v;
    m := iquo(A070939(n), 2);
    a := A030101(n);
    y := 0; t := 1;
    for x from 0 to 2*m-2 do
        if irem(a, 2) = 1 then y := y + 1
        else u := 2*m - x;
             v := m-1 - iquo(x+y,2);
             t := t + A037012(u,v);
             y := y - 1 fi;
        a := iquo(a, 2) od;
    A014137(m) - t end:
    seq(A215406(i),i=0..199); # Peter Luschny, Aug 10 2012
  • Mathematica
    A215406[n_] := Module[{m, d, a, y, t, x, u, v}, m = Quotient[Length[d = IntegerDigits[n, 2]], 2]; a = FromDigits[Reverse[d], 2]; y = 0; t = 1; For[x = 0, x <= 2*m - 2, x++, If[Mod[a, 2] == 1, y++, u = 2*m - x; v = m - Quotient[x + y, 2] - 1; t = t - Binomial[u - 1, v - 1] + Binomial[u - 1, v]; y--]; a = Quotient[a, 2]]; (1 - I*Sqrt[3])/2 - 4^(m + 1)*Gamma[m + 3/2]*Hypergeometric2F1[1, m + 3/2, m + 3, 4]/(Sqrt[Pi]*Gamma[m + 3]) - t]; Table[A215406[n] // Simplify, {n, 0, 86}] (* Jean-François Alcover, Jul 25 2013, translated and adapted from Peter Luschny's Maple program *)
  • Sage
    def A215406(n) : # CatalanRankGlobal(n)
        m = A070939(n)//2
        a = A030101(n)
        y = 0; t = 1
        for x in (1..2*m-1) :
            u = 2*m - x; v = m - (x+y+1)/2
            mn = binomial(u, v) - binomial(u, v-1)
            t += mn*(1 - a%2)
            y -= (-1)^a
            a = a//2
        return A014137(m) - t

A064638 Positions of non-crossing fixed-point-free involutions encoded by A014486 in A055089. Permutation of A064640.

Original entry on oeis.org

0, 1, 7, 23, 127, 415, 143, 659, 719, 5167, 16687, 5455, 26815, 28495, 5183, 16703, 5699, 36899, 38579, 5759, 36959, 40031, 40319, 368047, 1174447, 379567, 1901647, 1992367, 368335, 1174735, 389695, 2627455, 2718175, 391375, 2629135, 2799055
Offset: 0

Views

Author

Antti Karttunen, Oct 02 2001

Keywords

Crossrefs

Maple procedure binexp2pars given in A057501, permul in A060125.

Programs

  • Maple
    map(PermRevLexRank,map(NonCrossingTranspos, A014486));
    NonCrossingTranspos := n -> convert(NonCrossingTransposAux(binexp2pars(n),1),'permlist',binwidth(n));
    NonCrossingTransposAux := proc(s,ii) local e,p,i,j; i := ii; p := []; for e in s do p := permul(p,NonCrossingTransposAux(e,i+1)); j := i+CountParens(e)+1; p := permul(p,[[i,j]]); i := j+1; od; RETURN(p); end;
    CountParens := proc(s) local e,k; if(0 = nops(s)) then RETURN(0); fi; e := 0; for k in s do e := e+2+CountParens(k); od; RETURN(e); end;

A129599 Prime-factorization encoded partition code for the Łukasiewicz-word, variant of A129593.

Original entry on oeis.org

1, 3, 25, 25, 343, 35, 35, 343, 35, 14641, 847, 847, 847, 55, 847, 55, 847, 14641, 847, 55, 847, 847, 55, 371293, 24167, 24167, 1573, 1183, 24167, 1183, 1573, 24167, 1183, 1183, 1183, 1183, 65, 24167, 1183, 1183, 1183, 65, 1573, 1183, 24167
Offset: 0

Views

Author

Antti Karttunen, May 01 2007

Keywords

Comments

In addition to all the automorphisms whose signature permutation satisfies the more restricted condition A127301(SP(n)) = A127301(n) for all n, there are also general tree-rotating automorphisms like *A057501, *A057502, *A069771 and *A069772 that satisfy also the condition A129599(SP(n)) = A129599(n) for all n. However, in contrast to A129593 this is not invariant under the automorphism *A072797. A000041(n) distinct values (seem to) occur in each range [A014137(n)..A014138(n)].

Examples

			The terms A079436(5), A079436(6) and A079436(8) are 2010, 2100 and 1110. After adding one to each number except the first one we get 2121, 2211 and 1221, each one which produces partition 1+1+2+2. Converting it to prime-exponents like explained in A129595, we get 2^0 * 3^0 * 5^1 * 7^1 = 35, thus a(5) = a(6) = a(8) = 35.
		

Crossrefs

Variant: A129593.

Formula

Construction: add one to each number of the Łukasiewicz-word of a general plane tree encoded by A014486(n) (i.e. A079436(n)) except the first number, sort the numbers into ascending order and interpreting it as a partition of a natural number, encode it in the manner explained in A129595.

A082314 Involution of natural numbers: A057502-conjugate of A057164.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 8, 7, 6, 9, 11, 10, 12, 13, 21, 22, 20, 17, 18, 19, 16, 14, 15, 23, 28, 25, 30, 33, 24, 29, 26, 31, 34, 27, 32, 35, 36, 58, 62, 59, 63, 64, 57, 61, 54, 45, 48, 55, 46, 49, 50, 56, 60, 53, 44, 47, 51, 42, 37, 39, 52, 43, 38, 40, 41, 65, 79, 70, 84, 93
Offset: 0

Views

Author

Antti Karttunen, Apr 17 2003

Keywords

Crossrefs

a(n) = A057502(A069889(n)). Occurs in A073200 as row 2361759710983228099211. Cf. also A082313.
Number of cycles: A007123. Number of fixed-points: A001405. Max. cycle size: A046698. LCM of cycle sizes: A046698. (In range [A014137(n-1)..A014138(n-1)] of this permutation, possibly shifted one term left or right).

Formula

a(n) = A057502(A057164(A057501(n)))
Previous Showing 31-39 of 39 results.