login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A097710 Lower triangular matrix T, read by rows, such that row (n) is formed from the sums of adjacent terms in row (n-1) of the matrix square T^2, with T(0,0)=1. 12
1, 1, 1, 2, 3, 1, 7, 13, 7, 1, 41, 88, 61, 15, 1, 397, 951, 781, 257, 31, 1, 6377, 16691, 15566, 6231, 1041, 63, 1, 171886, 484490, 500057, 231721, 48303, 4161, 127, 1, 7892642, 23701698, 26604323, 13843968, 3406505, 374127, 16577, 255, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

Column 0 forms the number of tournament sequences (A008934). Column 1 forms A097711. Row sums form A093657. This triangle has the same row sums and first column terms as in rows 2^n, for n>=0, of triangle A093654.

LINKS

Paul D. Hanna, Table of n, a(n) for n = 0..495, of rows 0..30 of triangle in flattened form.

FORMULA

T(n, k) = T^2(n-1, k-1) + T^2(n-1, k) for n>=1 and k>1, with T(n, 1) = T^2(n-1, 1) and T(n,n) = 1 for n>=0, where T^2 is the matrix square of this triangle T.

EXAMPLE

Rows of this triangle T begin:

1;

1, 1;

2, 3, 1;

7, 13, 7, 1;

41, 88, 61, 15, 1;

397, 951, 781, 257, 31, 1;

6377, 16691, 15566, 6231, 1041, 63, 1;

171886, 484490, 500057, 231721, 48303, 4161, 127, 1;

7892642, 23701698, 26604323, 13843968, 3406505, 374127, 16577, 255, 1;

627340987, 1990327810, 2398645354, 1372974823, 385301161, 50838529, 2919199, 66049, 511, 1; ...

Rows of T^2 begin:

1;

2, 1;

7, 6, 1;

41, 47, 14, 1;

397, 554, 227, 30, 1;

6377, 10314, 5252, 979, 62, 1;

171886, 312604, 187453, 44268, 4035, 126, 1;

7892642, 15809056, 10795267, 3048701, 357804, 16323, 254, 1;

627340987, 1362986823, 1035658531, 337316292, 47984869, 2853660, 65539, 510, 1; ...

The sums of adjacent terms in row (n) of T^2 forms row (n+1) of T:

T(5,0) = T^2(4,0) = 397;

T(5,1) = T^2(4,0) + T^2(4,1) = 397 + 554 = 951;

T(5,2) = T^2(4,1) + T^2(4,2) = 554 + 227 = 781.

Rows of matrix inverse T^(-1) begins:

1;

-1, 1;

1, -3, 1;

-1, 8, -7, 1;

1, -25, 44, -15, 1;

-1, 111, -346, 208, -31, 1;

1, -809, 4045, -3720, 912, -63, 1;

-1, 10360, -77351, 99776, -35136, 3840, -127, 1; ...

which is a signed version of A097712.

MATHEMATICA

T[n_, k_] := T[n, k] = Which[n<0 || k>n, 0, n == k, 1, k == 0, Sum[T[n-1, j]*T[j, 0], {j, 0, n-1}], True, Sum[T[n-1, j]*T[j, k-1], {j, 0, n-1}] + Sum[T[n-1, j]*T[j, k], {j, 0, n-1}]]; Table[T[n, k], {n, 0, 8}, {k, 0, n}] // Flatten (* Jean-Fran├žois Alcover, Nov 23 2016, adapted from PARI *)

PROG

(PARI) /* Using Recurrence relation: */

{T(n, k) = if(n<0||k>n, 0, if(n==k, 1, if(k==0, sum(j=0, n-1, T(n-1, j)*T(j, 0)),  sum(j=0, n-1, T(n-1, j)*T(j, k-1)) + sum(j=0, n-1, T(n-1, j)*T(j, k)); )))}

for(n=0, 8, for(k=0, n, print1(T(n, k), ", ")); print(""))

(PARI) /* Faster: using Matrix generating method: */

{T(n, k) = my(M=matrix(2, 2, r, c, if(r>=c, 1))); for(i=1, n,

N=matrix(#M+1, #M+1, r, c, if(r>=c, if(r<=#M, M[r, c], if(c>1, (M^2)[r-1, c-1]) + if(c<=#M, (M^2)[r-1, c])) ));

M=N; ); M[n+1, k+1]}

for(n=0, 10, for(k=0, n, print1(T(n, k), ", ")); print("")) \\ Paul D. Hanna, Nov 27 2016

CROSSREFS

Cf. A008934, A097711, A093657, A093654.

Cf. A097712.

Sequence in context: A103364 A104027 A192363 * A171024 A109198 A081320

Adjacent sequences:  A097707 A097708 A097709 * A097711 A097712 A097713

KEYWORD

nonn,tabl

AUTHOR

Paul D. Hanna, Aug 22 2004

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 19 16:02 EST 2019. Contains 320311 sequences. (Running on oeis4.)