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A069015

a(n) = n! * 3^n * Sum_{i=1..n} 1/(i * 3^i).

1, 7, 65, 786, 11814, 212772, 4468932, 107259408, 2896044336, 86881692960, 2867099496480, 103215621790080, 4025409728814720, 169067214837239040, 7608024754854048000, 365185189540668672000, 18624444687496892160000

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..17.

FORMULA

E.g.f.: -log(1-x)/(1-3*x). - Vladeta Jovovic, Feb 07 2003

a(n) ~ n! * 3^n * log(3/2). - Vaclav Kotesovec, Oct 05 2013

From Seiichi Manyama, May 22 2025: (Start)

a(n) = 3 * n * a(n-1) + (n-1)!.

a(n) = (4*n-1) * a(n-1) - 3 * (n-1)^2 * a(n-2). (End)

MATHEMATICA

Rest[CoefficientList[Series[-Log[1-x]/(1-3*x), {x, 0, 20}], x]* Range[0, 20]!] (* Vaclav Kotesovec, Oct 05 2013 *)

CROSSREFS

Cf. A000254, A068102.

Sequence in context: A390374 A300488 A085283 * A097819 A152525 A272646

Adjacent sequences: A069012 A069013 A069014 * A069016 A069017 A069018

KEYWORD

easy,nonn

AUTHOR

Benoit Cloitre, Apr 14 2002

STATUS

approved

URL: https://oeis.org/A069015

⇱ A069015 - OEIS