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a(n) = n!/(floor(n/2)!*floor(n/3)!*floor(n/6)!).
2

%I #25 Aug 19 2024 11:42:49

%S 1,1,2,6,12,60,60,420,840,2520,5040,55440,13860,180180,360360,1081080,

%T 2162160,36756720,4084080,77597520,155195040,465585120,931170240,

%U 21416915520,1338557220,33463930500,66927861000,200783583000,401567166000,11645447814000,465817912560

%N a(n) = n!/(floor(n/2)!*floor(n/3)!*floor(n/6)!).

%H Seiichi Manyama, <a href="/A347304/b347304.txt">Table of n, a(n) for n = 0..2000</a>

%H Denis Hanson, <a href="https://doi.org/10.4153/CMB-1972-007-7">On the product of the primes</a>, Canadian Mathematical Bulletin 15.1 (1972): 33-37. See Section 3.

%o (PARI) a(n) = n!/((n\2)!*(n\3)!*(n\6)!); \\ _Seiichi Manyama_, Aug 28 2021

%o (Python)

%o from math import factorial

%o def A347304(n): return factorial(n)//factorial(n//2)//factorial(n//3)//factorial(n//6) # _Chai Wah Wu_, Aug 28 2021

%Y a(6*n) = A113424(n).

%Y Cf. A081125, A347302.

%K nonn

%O 0,3

%A _N. J. A. Sloane_, Aug 28 2021

%E a(0)=1 prepended by _Seiichi Manyama_, Aug 28 2021