login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A111845 Triangle P, read by rows, that satisfies [P^4](n,k) = P(n+1,k+1) for n>=k>=0, also [P^(4*m)](n,k) = [P^m](n+1,k+1) for all m, where [P^m](n,k) denotes the element at row n, column k, of the matrix power m of P, with P(k,k)=1 and P(k+1,1)=P(k+1,0) for k>=0. 5
1, 1, 1, 4, 4, 1, 40, 40, 16, 1, 1040, 1040, 544, 64, 1, 78240, 78240, 48960, 8320, 256, 1, 18504256, 18504256, 13110400, 2878720, 131584, 1024, 1, 14463224448, 14463224448, 11192599808, 2982187520, 180270080, 2099200, 4096, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

Column 0 and column 1 are equal for n>0.

LINKS

Table of n, a(n) for n=0..35.

FORMULA

Let q=4; the g.f. of column k of P^m (ignoring leading zeros) equals: 1 + Sum_{n>=1} (m*q^k)^n/n! * Product_{j=0..n-1} L(q^j*x) where L(x) satisfies: x = Sum_{n>=1} -(-1)^n/n!*Product_{j=0..n-1} L(q^j*x); L(x) equals the g.f. of column 0 of the matrix log of P (A111849).

EXAMPLE

Let q=4; the g.f. of column k of matrix power P^m is:

1 + (m*q^k)*L(x) + (m*q^k)^2/2!*L(x)*L(q*x) +

(m*q^k)^3/3!*L(x)*L(q*x)*L(q^2*x) +

(m*q^k)^4/4!*L(x)*L(q*x)*L(q^2*x)*L(q^3*x) + ...

where L(x) satisfies:

x = L(x) - L(x)*L(q*x)/2! + L(x)*L(q*x)*L(q^2*x)/3! -+ ...

and L(x) = x + 4/2!*x^2 + 56/3!*x^3 + 1728/4!*x^4 +...(A111849).

Thus the g.f. of column 0 of matrix power P^m is:

1 + m*L(x) + m^2/2!*L(x)*L(4*x) + m^3/3!*L(x)*L(4*x)*L(4^2*x) +

m^4/4!*L(x)*L(4*x)*L(4^2*x)*L(4^3*x) + ...

Triangle P begins:

1;

1,1;

4,4,1;

40,40,16,1;

1040,1040,544,64,1;

78240,78240,48960,8320,256,1;

18504256,18504256,13110400,2878720,131584,1024,1; ...

where P^4 shifts columns left and up one place:

1;

4,1;

40,16,1;

1040,544,64,1;

78240,48960,8320,256,1; ...

PROG

(PARI) P(n, k, q=4)=local(A=Mat(1), B); if(n<k || k<0, 0, for(m=1, n+1, B=matrix(m, m); for(i=1, m, for(j=1, i, if(j==i, B[i, j]=1, if(j==1, B[i, j]=(A^q)[i-1, 1], B[i, j]=(A^q)[i-1, j-1])); )); A=B); return(A[n+1, k+1]))

CROSSREFS

Cf. A111846 (column 0), A111847 (row sums), A111848 (matrix log), A111840 (q=3), A078536 (variant).

Sequence in context: A071207 A136214 A067328 * A120396 A141024 A173210

Adjacent sequences:  A111842 A111843 A111844 * A111846 A111847 A111848

KEYWORD

nonn,tabl

AUTHOR

Paul D. Hanna, Aug 23 2005

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 May 13 19:36 EDT 2021. Contains 343868 sequences. (Running on oeis4.)