

A212207


Triangle read by rows: coefficients of polynomials p_{n,n1}(x) arising in enumeration of twoline arrays.


0



1, 1, 1, 1, 3, 2, 1, 6, 9, 4, 1, 10, 26, 25, 8, 1, 15, 60, 95, 65, 16, 1, 21, 120, 280, 309, 161, 32, 1, 28, 217, 700, 1113, 924, 385, 64, 1, 36, 364, 1554, 3346, 3948, 2596, 897, 128, 1, 45, 576, 3150, 8820, 13902, 12864, 6957, 2049, 256, 1, 55, 870, 5940
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OFFSET

0,5


COMMENTS

These polynomials are defined in Section 3 of CarlitzRiordan (1971). Equation (3.14) claims to be a recurrence, which unfortunately I could not get to work. The coefficients of the polynomials A_n(x) = a_{n,n}(x) which appear in (3.14) are the Narayama numbers A001263.


LINKS

Table of n, a(n) for n=0..58.
Carlitz, L. and Riordan, John. Enumeration of some twoline arrays by extent. J. Combinatorial Theory Ser. A 10 1971 271283. MR0274301(43 #66).
L. Carlitz and J. Riordan, Enumeration of some twoline arrays by extent, J. Combinatorial Theory Ser. A 10 1971 271283 (MR274301 Review by Richard P. Stanley)


FORMULA

G.f.: N(x,y)/(1N(x,y)^2), where N(x,y) is g.f. of Narayana numbers (A001263). Vladimir Kruchinin, Apr 10 2018


EXAMPLE

Triangle begins:
1
1 1
1 3 2
1 6 9 4
1 10 26 25 8
...


PROG

(PARI) {T(n, k) = if( n < k  k < 0, 0, sum( j=0, k, binomial( n+1, k+1) * binomial( n+1, kj) * if( j%2, (n+1 +jk), k+1)) / (n+1))} /* Michael Somos, Aug 22 2012 */


CROSSREFS

Cf. A001263.
Sequence in context: A052174 A227790 A181897 * A111049 A211955 A088617
Adjacent sequences: A212204 A212205 A212206 * A212208 A212209 A212210


KEYWORD

nonn,tabl


AUTHOR

N. J. A. Sloane, May 15 2012


STATUS

approved



