cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A132625 Triangle T, read by rows, where row n+1 of T = row n of T^(2^n) with appended '1' for n>=0 with T(0,0)=1.

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 14, 4, 1, 1, 336, 60, 8, 1, 1, 25836, 2960, 248, 16, 1, 1, 6251504, 454072, 24800, 1008, 32, 1, 1, 4838830976, 216266368, 7603952, 202944, 4064, 64, 1, 1, 12344615283200, 328381917376, 7190266752, 124427232, 1641856, 16320, 128, 1, 1
Offset: 0

Views

Author

Paul D. Hanna, Aug 25 2007, Jan 07 2008

Keywords

Comments

Let R_{n} equal row n of square array A136555, where A136555(n,k) = C(2^k + n-1, k); this triangle transforms rows of A136555: T * R_{n} = R_{n+1} for n>=0.

Examples

			Triangle begins:
1;
1, 1;
2, 1, 1;
14, 4, 1, 1;
336, 60, 8, 1, 1;
25836, 2960, 248, 16, 1, 1;
6251504, 454072, 24800, 1008, 32, 1, 1;
4838830976, 216266368, 7603952, 202944, 4064, 64, 1, 1;
12344615283200, 328381917376, 7190266752, 124427232, 1641856, 16320, 128, 1, 1; ...
GENERATE T FROM MATRIX POWERS OF T.
Matrix power T^4 begins:
1;
4, 1;
14, 4, 1; <-- row 3 of T
96, 22, 4, 1;
1941, 316, 38, 4, 1;
129206, 14185, 1140, 70, 4, 1; ...
where row 3 of T = row 2 of T^(2^2) with appended '1'.
Matrix power T^8 begins:
1;
8, 1;
44, 8, 1;
336, 60, 8, 1; <-- row 4 of T
6062, 872, 92, 8, 1;
345596, 35734, 2712, 156, 8, 1; ...
where row 4 of T = row 3 of T^(2^3) with appended '1'.
Matrix power T^16 begins:
1;
16, 1;
152, 16, 1;
1504, 184, 16, 1;
25836, 2960, 248, 16, 1; <-- row 5 of T
1197304, 109500, 7408, 376, 16, 1; ...
where row 5 of T = row 4 of T^(2^4) with appended '1'.
Alternate generating method:
RoW 3: start with '1' followed by (2^2 - 1) zeros;
take partial sums and append (2^1 - 1) zero;
take partial sums twice more:
(1), 0, 0, 0;
1, 1, 1, (1), 0;
1, 2, 3, 4, (4);
1, 3, 6, 10, (14);
the final nonzero terms form row 3: [14, 4, 1, 1].
Row 4: start with '1' followed by (2^3 - 1) zeros;
take partial sums and append (2^2 - 1) zeros;
take partial sums and append (2^1 - 1) zero;
take partial sums twice more:
(1), 0, 0, 0, 0, 0, 0, 0;
1, 1, 1, 1, 1, 1, 1, (1), 0, 0, 0;
1, 2, 3, 4, 5, 6, 7, 8, 8, 8, (8), 0;
1, 3, 6, 10, 15, 21, 28, 36, 44, 52, 60, (60);
1, 4, 10, 20, 35, 56, 84, 120, 164, 216, 276, (336);
the final nonzero terms form row 4: [336, 60, 8, 1, 1].
Continuing in this way produces all the rows of this triangle.
		

Crossrefs

Cf. variants: A101479, A132610, A132615; columns: A132626, A132627.
Cf. A136555.

Programs

  • PARI
    T(n, k)=local(A=Mat(1), B); for(m=1, n+1, B=matrix(m, m); for(i=1, m, for(j=1, i, if(j==i, B[i, j]=1, B[i, j]=(A^(2^(i-2)))[i-1, j]); )); A=B); return( ((A)[n+1, k+1]))
    
  • PARI
    /* Generate using partial sums method (faster) */ T(n, k)=local(A=vector(n+1), p); A[1]=1; for(j=1, n-k, p=2^n-2^(n-j)-j; A=Vec((Polrev(A)+x*O(x^p))/(1-x))); A[p+1]
    
  • PARI
    /* As Row Transformation of Square Array A136555(n,k) = C(2^k + n-1, k): */ T(n,k)=local(M=matrix(n+2,n+2,r,c,binomial(2^(c-1)+r-2,c-1)), N=matrix(n+1,n+1,r,c,M[r,c]),P=matrix(n+1,n+1,r,c,M[r+1,c]),R=P~*N~^-1); R[n+1,k+1]