A337355 a(n) is the denominator of Product_{i=0..n-1} (n-i)^((-1)^ceiling(i/2)).

1, 1, 2, 3, 6, 5, 5, 63, 56, 4, 225, 77, 1232, 312, 65, 2695, 1408, 14144, 9945, 92169, 53504, 28288, 41769, 370139, 447488, 217600, 502775, 1427679, 2684928, 2524160, 10414625, 132774147, 443908096, 2375680, 1168520925, 3129357, 18644140032, 35160064, 1108596775, 2318853537

Offset: 1

Author

Devansh Singh, Aug 24 2020

Keywords

• nonn
• frac

Examples

			a(5) = denominator of (5*2)/(4*3) = 6.
		

Crossrefs

Cf. A337354 (numerators).

Programs

PARI

a(n) = {denominator(prod(i=0, n-1, (n-i)^(-1)^((i+1)\2)))} \\ Andrew Howroyd, Aug 25 2020

Extensions

Terms a(31) and beyond from Andrew Howroyd, Aug 25 2020