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A187122
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A diagonal of triangle A187120.
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4
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1, 9, 81, 855, 10758, 159633, 2750067, 54178485, 1204443432, 29871630837, 818490738402, 24571782872034, 802459134168208, 28332664539686670, 1075700621922471621, 43710289920461797346, 1893011243289589171122
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OFFSET
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3,2
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COMMENTS
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Definition of triangle: A187120(n,k) = [y^k] R_{n-1}(y+y^2) for k=3..n, n>3, where R_n(y) is the n-th row polynomial starting with R_3(y)=y^3.
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LINKS
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Table of n, a(n) for n=3..19.
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FORMULA
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Equals column 2 in the matrix cube of triangle A135080.
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PROG
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(PARI) {a(n)=local(Rn=y^3); for(m=3, n+1, Rn=subst(truncate(Rn), y, y+y^2+O(y^m))); polcoeff(Rn, n, y)}
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CROSSREFS
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Cf. A187120, A135083, A187121, A187123, A187124.
Sequence in context: A077364 A077486 A233021 * A113361 A180737 A068881
Adjacent sequences: A187119 A187120 A187121 * A187123 A187124 A187125
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna, Mar 08 2011
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STATUS
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approved
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