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A008280 Boustrophedon version of triangle of Euler-Bernoulli or Entringer numbers read by rows. 12
1, 0, 1, 1, 1, 0, 0, 1, 2, 2, 5, 5, 4, 2, 0, 0, 5, 10, 14, 16, 16, 61, 61, 56, 46, 32, 16, 0, 0, 61, 122, 178, 224, 256, 272, 272, 1385, 1385, 1324, 1202, 1024, 800, 544, 272, 0, 0, 1385, 2770, 4094, 5296, 6320, 7120, 7664, 7936, 7936 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,9

COMMENTS

The earliest known reference for this triangle is Seidel (1877). - Don Knuth, Jul 13 2007

Sum of row n = A000111(n+1). - Reinhard Zumkeller, Nov 01 2013

REFERENCES

Arnold, V. I., Bernoulli-Euler updown numbers associated with function singularities, their combinatorics and arithmetics, Duke Math. J. 63 (1991), 537-555.

V. I. Arnold, The calculus of snakes and the combinatorics of Bernoulli, Euler and Springer numbers of Coxeter groups, Uspekhi Mat. nauk., 47 (#1, 1992), 3-45 = Russian Math. Surveys, Vol. 47 (1992), 1-51.

M. D. Atkinson: Zigzag permutations and comparisons of adjacent elements, Information Processing Letters 21 (1985), 187-189.

M. D. Atkinson: Partial orders and comparison problems, Sixteenth Southeastern Conference on Combinatorics, Graph Theory and Computing, (Boca Raton, Feb 1985), Congressus Numerantium 47, 77-88.

J. H. Conway and R. K. Guy, The Book of Numbers, Copernicus Press, NY, 1996, p. 110.

Dominique Foata and Guo-Niu Han, Seidel Triangle Sequences and Bi-Entringer Numbers, November 20, 2013; http://www-irma.u-strasbg.fr/~foata/paper/pub123Seidel.pdf

A. J. Kempner, On the shape of polynomial curves, Tohoku Math. J., 37 (1933), 347-362.

C. Poupard, De nouvelles significations enumeratives des nombres d'Entringer, Discrete Math., 38 (1982), 265-271.

L. Seidel, Ueber eine einfache Entstehungsweise der Bernoulli'schen Zahlen und einiger verwandten Reihen, Sitzungsberichte der mathematisch-physikalischen Classe der königlich bayerischen Akademie der Wissenschaften zu München, volume 7 (1877), 157-187.

R. P. Stanley, Enumerative Combinatorics, volume 1, second edition, chapter 1, exercise 141, Cambridge University Press (2012), p. 128, 174, 175.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

B. Gourevitch, L'univers de Pi

Peter Luschny, An old operation on sequences: the Seidel transform

J. Millar, N. J. A. Sloane and N. E. Young, A new operation on sequences: the Boustrophedon on transform, J. Combin. Theory, 17A 44-54 1996 (Abstract, pdf, ps).

R. Street, Trees, permutations and the tangent function

Wikipedia, Boustrophedon_transform

Index entries for sequences related to boustrophedon transform

EXAMPLE

This version of the triangle begins:

.............1

...........0...1

.........1...1...0

.......0...1...2...2

.....5...5...4...2...0

...0...5..10..14..16..16

See A008281 and A108040 for other versions.

MATHEMATICA

max = 9; t[0, 0] = 1; t[n_, m_] /; n < m || m < 0 = 0; t[n_, m_] := t[n, m] = Sum[t[n-1, n-k], {k, m}]; tri = Table[t[n, m], {n, 0, max}, {m, 0, n}]; Flatten[ {Reverse[#[[1]]], #[[2]]} & /@ Partition[tri, 2]] (* Jean-François Alcover, Oct 24 2011 *)

PROG

(Sage) # Algorithm of L. Seidel (1877)

# Prints the first n rows of the triangle.

def A008280_triangle(n) :

    A = {-1:0, 0:1}

    k = 0; e = 1

    for i in range(n) :

        Am = 0

        A[k + e] = 0

        e = -e

        for j in (0..i) :

            Am += A[k]

            A[k] = Am

            k += e

        print [A[z] for z in (-i//2..i//2)]

A008280_triangle(10) # Peter Luschny, Jun 02 2012

(Haskell)

a008280 n k = a008280_tabl !! n !! k

a008280_row n = a008280_tabl !! n

a008280_tabl = ox True a008281_tabl where

  ox turn (xs:xss) = (if turn then reverse xs else xs) : ox (not turn) xss

-- Reinhard Zumkeller, Nov 01 2013

CROSSREFS

Cf. A008281, A108040, A058257.

Cf. A000657 (central terms); A227862.

Sequence in context: A210802 A236935 * A239005 A213187 A195710 A200997

Adjacent sequences:  A008277 A008278 A008279 * A008281 A008282 A008283

KEYWORD

nonn,tabl,nice

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified April 18 19:33 EDT 2014. Contains 240733 sequences.