

A051159


Triangular array made of three copies of Pascal's triangle.


20



1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 2, 0, 1, 1, 1, 2, 2, 1, 1, 1, 0, 3, 0, 3, 0, 1, 1, 1, 3, 3, 3, 3, 1, 1, 1, 0, 4, 0, 6, 0, 4, 0, 1, 1, 1, 4, 4, 6, 6, 4, 4, 1, 1, 1, 0, 5, 0, 10, 0, 10, 0, 5, 0, 1, 1, 1, 5, 5, 10, 10, 10, 10, 5, 5, 1, 1, 1, 0, 6, 0, 15, 0, 20, 0, 15, 0, 6, 0, 1, 1, 1, 6, 6, 15, 15, 20, 20, 15, 15, 6, 6, 1, 1
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OFFSET

0,13


COMMENTS

Computing each term modulo 2 also gives A047999, i.e. A051159[n] mod 2 = A007318[n] mod 2 for all n. (The triangle is paritywise isomorphic to Pascal's Triangle)  Antti Karttunen
5th row/column gives entries of A000217 (triangular numbers C(n+1,2)) repeated twice and every other entry in 6th row/column form A000217. 7th row/column gives entries of A000292 (Tetrahedral (or pyramidal) nos: C(n+3,3)) repeated twice and every other entry in 8th row/column form A000292. 9th row/column gives entries of A000332 (binomial coefficients binomial(n,4)) repeated twice and every other entry in 10th row/column form A000332. 11th row/column gives entries of A000389 (binomial coefficients C(n,5)) repeated twice and every other entry in 12th row/column form A000389.  Gerald McGarvey, Aug 21 2004
If Sum_{k=0..n}A(k)*T(n,k)=B(n), the sequence B is the SD transform of the sequence A.  Philippe Deléham, Aug 02 2006
Number of nbead blackwhite reversible strings with k black beads; also binary grids; string is palindromic.  Yosu Yurramendi, Aug 07 2008
Row sums give A016116(n+2).  Yosu Yurramendi, Aug 07 2008
Coefficients in expansion of (x + y)^n where x and y anticommute (y x = x y), that is, qbinomial coefficients when q = 1.  Michael Somos, Feb 16 2009
The sequence of coefficients of a general polynomial recursion that links at w=2 to the Pascal triangle is here w=0. Row sums are: {1, 2, 2, 4, 4, 8, 8, 16, 16, 32, 32, 64,...}.  Roger L. Bagula and Gary W. Adamson, Dec 04 2009
T(n,k) is the number of palindromic compositions of n with exactly k parts. T(7,5) = 3 because we have: 1+1+3+1+1, 2+1+1+1+2, 1+2+1+2+1.  Geoffrey Critzer, Mar 15 2014


REFERENCES

S. J. Cyvin et al., Unbranched catacondensed polygonal systems containing hexagons and tetragons, Croatica Chem. Acta, 69 (1996), 757774.


LINKS

Reinhard Zumkeller, Rows n = 0..120 of triangle, flattened
M. E. Horn, The Didactical Relevance of the Pauli Pascal Triangle [Michael Somos]
F. AlKharousi, R. Kehinde, A. Umar, Combinatorial results for certain semigroups of partial isometries of a finite chain, The Australasian Journal of Combinatorics, Volume 58 (3) (2014), 363375.
Index entries for triangles and arrays related to Pascal's triangle


FORMULA

T(n, k) = T(n1, k1) + T(n1, k) if n odd or k even, else 0. T(0, 0) = 1.
T(n, k) = T(n2, k2) + T(n2, k). T(0, 0 ) = T(1, 0) = T(1, 1) = 1.
Square array made by setting first row/column to 1's (A(i, 0) = A(0, j) = 1); A(1, 1) = 0; A(1, j) = A(1, j2); A(i, 1) = A(i2, 1); other entries A(i, j) = A(i2, j) + A(i, j2).  Gerald McGarvey, Aug 21 2004
Sum_{k=0..n} k * T(n,k) = A093968(n); A093968 = SD transform of A001477.  Philippe Deléham, Aug 02 2006
Equals 2*A034851  A007318.  Gary W. Adamson, Dec 31 2007. [Corrected by Yosu Yurramendi, Aug 07 2008]
A051160(n, k) = (1)^floor(k/2) * A051159(n, k).
Sum_{k = 0..n} T(n,k)*x^k = A000012(n), A016116(n+1), A056487(n), A136859(n+2) for x = 0, 1, 2, 3 respectively.  Philippe Deléham, Mar 11 2014
G.f.: (1+x+x*y)/(1x^2y^2*x^2).  Philippe Deléham, Mar 11 2014


EXAMPLE

Triangle starts:
{1},
{1, 1},
{1, 0, 1},
{1, 1, 1, 1},
{1, 0, 2, 0, 1},
{1, 1, 2, 2, 1, 1},
{1, 0, 3, 0, 3, 0, 1},
{1, 1, 3, 3, 3, 3, 1, 1},
{1, 0, 4, 0, 6, 0, 4, 0, 1},
{1, 1, 4, 4, 6, 6, 4, 4, 1, 1},
{1, 0, 5, 0, 10, 0, 10, 0, 5, 0, 1},
{1, 1, 5, 5, 10, 10, 10, 10, 5, 5, 1, 1}
...  Roger L. Bagula and Gary W. Adamson, Dec 04 2009


MAPLE

T:= proc(n, k) option remember; `if`(n=0 and k=0, 1,
`if`(n<0 or k<0, 0, `if`(irem(n, 2)=1 or
irem(k, 2)=0, T(n1, k1) + T(n1, k), 0)))
end:
seq(seq(T(n, k), k=0..n), n=0..14); # Alois P. Heinz, Jul 12 2014


MATHEMATICA

T[ n_, k_] := QBinomial[n, k, 1] (* Michael Somos, Jun 14 2011; since V7 *)
Clear[p, n, x, a]
w = 0;
p[x, 1] := 1;
p[x_, n_] := p[x, n] = If[Mod[n, 2] == 0, (x + 1)*p[x, n  1], (x^2 + w*x + 1)^Floor[n/2]]
a = Table[CoefficientList[p[x, n], x], {n, 1, 12}]
Flatten[a] (* Roger L. Bagula and Gary W. Adamson, Dec 04 2009 *)


PROG

(PARI) {T(n, k) = binomial(n%2, k%2) * binomial(n\2, k\2)}
(Haskell)
a051159 n k = a051159_tabl !! n !! k
a051159_row n = a051159_tabl !! n
a051159_tabl = [1] : f [1] [1, 1] where
f us vs = vs : f vs (zipWith (+) ([0, 0] ++ us) (us ++ [0, 0]))
 Reinhard Zumkeller, Apr 25 2013


CROSSREFS

Cf. A007318. A051160.
Cf. A016116, A034851, A169623.
Cf. A036355.
Sequence in context: A035196 A158020 A051160 * A035697 A135549 A124737
Adjacent sequences: A051156 A051157 A051158 * A051160 A051161 A051162


KEYWORD

nonn,tabl,easy,nice


AUTHOR

Michael Somos, Oct 14 1999


STATUS

approved



