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A080421 (n+1)(n+2)(n+9)3^n/18. 2
1, 10, 66, 360, 1755, 7938, 34020, 139968, 557685, 2165130, 8227494, 30705480, 112842639, 409209570, 1466777160, 5203870272, 18294856425, 63795240522, 220829678730, 759344158440, 2595329855811, 8821564534530, 29832927334956 (list; graph; refs; listen; history; internal format)
OFFSET

0,2

FORMULA

G.f.: (1-2x)/(1-3x)^4

a(n)=A006503(n+1)*3^(n-1)

CROSSREFS

T(n, 3) in triangle A080419

Sequence in context: A159838 A024391 A074362 * A004310 A026853 A177452

Adjacent sequences:  A080418 A080419 A080420 * A080422 A080423 A080424

KEYWORD

easy,nonn

AUTHOR

Paul Barry (pbarry(AT)wit.ie), Feb 19 2003

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Last modified February 13 16:42 EST 2012. Contains 205523 sequences.