A123308 - OEIS

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A123308

Column 2 of triangle A123305.

1, 3, 18, 144, 1422, 16848, 235458, 3827628, 71466174, 1515031920, 36091609434, 957367079244, 28050237910926, 901359663633000, 31567805908329330, 1198307340146774844, 49060139971072916142, 2156816501291429473248

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OFFSET

0,2

COMMENTS

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).

LINKS

Table of n, a(n) for n=0..17.

CROSSREFS

Cf. A123305, A123306, A123307, A123309, A123310, A123311.

Sequence in context: A107708 A224992 A289428 * A374864 A177383 A074525

Adjacent sequences: A123305 A123306 A123307 * A123309 A123310 A123311

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Sep 24 2006

STATUS

approved