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Search: id:A104982
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| 1, 4, 21, 133, 977, 8135, 75609, 775667, 8707057, 106185715, 1398451353, 19786121467, 299384925569, 4825081148819, 82531968286569, 1493412479919371, 28504390805515921, 572363196501249667, 12061937537478658809
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OFFSET
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0,2
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COMMENT
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Equals one-half of column 0 (after initial term) in triangle A104988, which equals the matrix square of triangle A104980.
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FORMULA
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a(n) = A104988(n+1, 0)/2 for n>=0.
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PROGRAM
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(PARI) {a(n)=if(n<0, 0, (matrix(n+4, n+4, m, j, if(m==j, 1, if(m==j+1, -m+1, -polcoeff((1-1/sum(i=0, m, i!*x^i))/x+O(x^m), m-j-1))))^-1)[n+4, 4])}
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CROSSREFS
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Cf. A104980, A104988.
Sequence in context: A078591 A090366 A131965 this_sequence A001909 A052852 A121124
Adjacent sequences: A104979 A104980 A104981 this_sequence A104983 A104984 A104985
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Apr 10 2005
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