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A101481 Column 0 of triangular matrix T=A101479, in which row n equals row (n-1) of T^(n-1) followed by '1'. 3
1, 1, 1, 3, 19, 191, 2646, 46737, 1003150, 25330125, 735180292, 24103027865, 880627477269, 35469795883964, 1561107221731851, 74528004538789830, 3835467005270307663, 211648845813188932595, 12465477924609075602136 (list; graph; refs; listen; history; internal format)
OFFSET

0,4

EXAMPLE

This sequence can also be generated in the following manner.

Start a table with the all 1's sequence in row 0; from then on, row n+1 can be formed from row n by dropping the initial n-1 terms of row n and taking partial sums of the remaining terms to obtain row n+1.

The table below illustrates this method:

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, ...;

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, ...;

[1], 3, 6, 10, 15, 21, 28, 36, 45, 55, 66, 78, 91, ...;

[3, 9], 19, 34, 55, 83, 119, 164, 219, 285, 363, 454, ...;

[19, 53, 108], 191, 310, 474, 693, 978, 1341, 1795, 2354, ...;

[191, 501, 975, 1668], 2646, 3987, 5782, 8136, 11169, 15017, ...;

[2646, 6633, 12415, 20551, 31720], 46737, 66570, 92358, ...; ...;

In the above table, drop the initial n-1 terms in row n (enclosed in square brackets) and then take partial sums to obtain row n+1 for n>=1;

this sequence then forms the first column of the resultant table.

Note: column k of the above table equals column 0 of matrix power T^(k+1) where T=A101479, for k>=0.

PROG

(PARI) {a(n)=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^(i-2))[i-1, j]); )); A=B); return(A[n+1, 1])}

CROSSREFS

Cf. A101479, A101482, A101483.

Sequence in context: A141623 A090354 A119394 * A155805 A001517 A080893

Adjacent sequences:  A101478 A101479 A101480 * A101482 A101483 A101484

KEYWORD

nonn

AUTHOR

Paul D. Hanna (pauldhanna(AT)juno.com), Jan 21 2005

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Last modified February 17 06:26 EST 2012. Contains 205997 sequences.