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A105619
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Matrix inverse of triangle A105615.
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2
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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)
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OFFSET
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0,2
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COMMENTS
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Except for the initial few terms, all columns are equal to negative A000698 (related to double factorials).
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LINKS
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Table of n, a(n) for n=0..54.
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EXAMPLE
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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; ...
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PROG
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(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])}
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CROSSREFS
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Cf. A105615, A000698, A105620 (matrix square-root).
Sequence in context: A177701 A119765 A077901 * A121439 A009205 A086754
Adjacent sequences: A105616 A105617 A105618 * A105620 A105621 A105622
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KEYWORD
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sign,tabl
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AUTHOR
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Paul D. Hanna, Apr 16 2005
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STATUS
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approved
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