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A035324 A convolution triangle of numbers, generalizing Pascal's triangle A007318. 21
1, 3, 1, 10, 6, 1, 35, 29, 9, 1, 126, 130, 57, 12, 1, 462, 562, 312, 94, 15, 1, 1716, 2380, 1578, 608, 140, 18, 1, 6435, 9949, 7599, 3525, 1045, 195, 21, 1, 24310, 41226, 35401, 19044, 6835, 1650, 259, 24, 1, 92378, 169766, 161052, 97954, 40963, 12021, 2450 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Replacing each '2' in the recurrence by '1' produces Pascal's triangle A007318(n-1,m-1). The columns appear as A001700, A008549, A045720, A045894, A035330...

Triangle T(n,k), 1<=k<=n, given by (0, 3/1, 1/3, 5/3, 3/5, 7/5, 5/7, 9/7, 7/9, 11/9, 9/11, ...) DELTA (1, 0, 0, 0, 0, 0, 0, 0, 0, ...) where DELTA is the operator defined in A084938. - Philippe Deléham, Jan 28 2012

Riordan array (1, c(x)/sqrt(1-4x)) where c(x) = g.f. for Catalan numbers A000108, first column (k = 0) omitted. - Philippe Deléham, Jan 28 2012

LINKS

Reinhard Zumkeller, Rows n = 1..120 of triangle, flattened

W. Lang, On generalizations of Stirling number triangles, J. Integer Seqs., Vol. 3 (2000), #00.2.4.

W. Lang, First 10 rows.

FORMULA

a(n+1, m) = 2*(2*n+m)*a(n, m)/(n+1) + m*a(n, m-1)/(n+1), n >= m >= 1; a(n, m) := 0, n<m; a(n, 0) := 0, a(1, 1)=1;

G.f. for column m: ((x*c(x)/sqrt(1-4*x))^m)/x, where c(x) = g.f. for Catalan numbers A000108.

a(n, m) =: s2(3; n, m).

With offset 0 (0<=k<=n), T(n,k) = Sum_{j>=0} A039598(n,j)*binomial(j,k). - Philippe Deléham, Mar 30 2007

T(n+1,n) = 3*n = A008585(n).

T(n,k) = T(n-1,k-1) + 3*T(n-1,k) + Sum_{i>=0} T(n-1,k+1+i)*(-1)^i. - Philippe Deléham, Feb 23 2012

T(n,m) = Sum_{k=m..n} k*binomial(k-1,k-m)*2^(k-m)*binomial(2*n-k-1,n-k))/n. - Vladimir Kruchinin, Aug 07 2013

EXAMPLE

Triangle begins:

1

3     1

10    6   1

35   29   9   1

126 130  57  12   1

462 562 312  94  15   1

Triangle (0,3,1/3,5/3,3/5,...) DELTA (1,0,0,0,0,0, ...) has an additional first column (1,0,0,...).

MATHEMATICA

a[n_, m_] /; n >= m >= 1 := a[n, m] = 2*(2*(n-1) + m)*(a[n-1, m]/n) + m*(a[n-1, m-1]/n); a[n_, m_] /; n < m = 0; a[n_, 0] = 0; a[1, 1] = 1; Flatten[ Table[ a[n, m], {n, 1, 10}, {m, 1, n}]] (* Jean-François Alcover, Feb 21 2012, from first formula *)

PROG

(Haskell)

a035324 n k = a035324_tabl !! (n-1) !! (k-1)

a035324_row n = a035324_tabl !! (n-1)

a035324_tabl = map snd $ iterate f (1, [1]) where

   f (i, xs)  = (i + 1, map (`div` (i + 1)) $

      zipWith (+) ((map (* 2) $ zipWith (*) [2 * i + 1 ..] xs) ++ [0])

                  ([0] ++ zipWith (*) [2 ..] xs))

-- Reinhard Zumkeller, Jun 30 2013

(Sage)

@cached_function

def T(n, k):

    if n == 0: return n^k

    return sum(binomial(2*i-1, i)*T(n-1, k-i) for i in (1..k-n+1))

A035324 = lambda n, k: T(k, n)

for n in (1..8): print [A035324(n, k) for k in (1..n)] # Peter Luschny, Aug 16 2016

CROSSREFS

Cf. A000108, A007318, A039598.

Row sums: A049027(n), n >= 1.

Alternating row sums give A000108 (Catalan numbers).

If offset 0 (n >= m >= 0): convolution triangle based on A001700 (central binomial coeffs. of odd order).

Sequence in context: A171509 A171505 A134283 * A171814 A091965 A171568

Adjacent sequences:  A035321 A035322 A035323 * A035325 A035326 A035327

KEYWORD

easy,nice,nonn,tabl

AUTHOR

Wolfdieter Lang

STATUS

approved

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Last modified February 24 05:37 EST 2018. Contains 299597 sequences. (Running on oeis4.)