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a(n) = (n!+3)/3.
4

%I #14 Oct 14 2024 01:38:03

%S 3,9,41,241,1681,13441,120961,1209601,13305601,159667201,2075673601,

%T 29059430401,435891456001,6974263296001,118562476032001,

%U 2134124568576001,40548366802944001,810967336058880001

%N a(n) = (n!+3)/3.

%H Amiram Eldar, <a href="/A139150/b139150.txt">Table of n, a(n) for n = 3..450</a>

%e (2!+3)/3 = 5/3 is not an integer.

%e a(3) = (3!+3)/3 = 3.

%t Table[(n! + 3)/3, {n, 3, 30}]

%Y Cf. A007749, A020458, A082672, A089085, A089130, A117141, A139056-A139066, A139068, A137390, A139070-A139075, A139148-A139157, A139159, A139160, A139161, A139162.

%K nonn

%O 3,1

%A _Artur Jasinski_, Apr 11 2008

%E Name corrected by _Amiram Eldar_, Oct 13 2024