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A123308
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Column 2 of triangle A123305.
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7
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1, 3, 18, 144, 1422, 16848, 235458, 3827628, 71466174, 1515031920, 36091609434, 957367079244, 28050237910926, 901359663633000, 31567805908329330, 1198307340146774844, 49060139971072916142, 2156816501291429473248
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OFFSET
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0,2
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COMMENTS
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Triangle T=A123305 is defined by: (column k of T) = (k+1)*(column k of T^2) shifted to have an initial '1'; thus this sequence shifted left equals 3 times column 2 of T^2 (matrix square of A123305).
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LINKS
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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