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A323716
a(n) = Product_{k=0..n} (3^k + 1).
4
2, 8, 80, 2240, 183680, 44817920, 32717081600, 71584974540800, 469740602936729600, 9246374028206585446400, 545998386365598870609920000, 96722522147893108730806108160000, 51402410615320609490117059732766720000
OFFSET
0,1
LINKS
FORMULA
a(n) ~ c * 3^(n*(n+1)/2), where c = A132323 = QPochhammer[-1, 1/3] = 3.12986803713402307587769821345767...
MATHEMATICA
Table[Product[3^k+1, {k, 0, n}], {n, 0, 12}]
Table[QPochhammer[-1, 3, n+1], {n, 0, 12}]
PROG
(PARI) a(n) = prod(k=0, n, 3^k+1); \\ Michel Marcus, Jan 25 2019
(Magma) [(&*[3^j+1: j in [0..n]]): n in [0..20]]; // G. C. Greubel, Aug 30 2023
(SageMath) [product(3^j+1 for j in range(n+1)) for n in range(21)] # G. C. Greubel, Aug 30 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Jan 25 2019
STATUS
approved