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A105619 Matrix inverse of triangle A105615. 2
1, -2, 1, -2, -4, 1, -10, -2, -6, 1, -74, -10, -2, -8, 1, -706, -74, -10, -2, -10, 1, -8162, -706, -74, -10, -2, -12, 1, -110410, -8162, -706, -74, -10, -2, -14, 1, -1708394, -110410, -8162, -706, -74, -10, -2, -16, 1, -29752066, -1708394, -110410, -8162, -706, -74, -10, -2, -18, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Except for the initial few terms, all columns are equal to negative A000698 (related to double factorials).

LINKS

Table of n, a(n) for n=0..54.

EXAMPLE

Triangle begins:

1;

-2,1;

-2,-4,1;

-10,-2,-6,1;

-74,-10,-2,-8,1;

-706,-74,-10,-2,-10,1;

-8162,-706,-74,-10,-2,-12,1;

-110410,-8162,-706,-74,-10,-2,-14,1;

-1708394,-110410,-8162,-706,-74,-10,-2,-16,1; ...

PROG

(PARI) T(n, k)=if(n<k || k<0, 0, matrix(n+1, n+1, m, j, if(m>=j, if(m==j, 1, if(m==j+1, -2*j, polcoeff(1/sum(i=0, m-j, (2*i)!/i!/2^i*x^i)+O(x^m), m-j)))))[n+1, k+1])

CROSSREFS

Cf. A105615, A000698, A105620 (matrix square-root).

Sequence in context: A119765 A303325 A077901 * A302212 A302460 A303242

Adjacent sequences:  A105616 A105617 A105618 * A105620 A105621 A105622

KEYWORD

sign,tabl

AUTHOR

Paul D. Hanna, Apr 16 2005

STATUS

approved

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Last modified January 18 00:48 EST 2022. Contains 350410 sequences. (Running on oeis4.)