A081954 -id:A081954 - cp's OEIS frontend

A081955 a(n) = 2^r*3^s where r = n(n+1)/2 and s = n(n-1)/2.

1, 2, 24, 1728, 746496, 1934917632, 30091839012864, 2807929681968365568, 1572081206902992767287296, 5280985496827154199640037916672, 106440332834866049138191223105387495424, 12872079797383178927229037635891253693013557248

Offset: 0

Amarnath Murthy, Apr 02 2003

nonn

Sequence contains the product of a row in A081954.

Cf. A025192, A081954, A081956.

Do[Print[2^(n*(n+1)/2)*3^(n*(n-1)/2)], {n, 10}] (* Ryan Propper, Jun 15 2005 *)

{a(n) = 3^(n*(n-1)/2) * 2^(n*(n+1)/2)} /* Michael Somos, Dec 17 2009 */

a(n+1) = 2^(n+1)*3^n*a(n), a(1) = 2. - Ryan Propper, Jun 15 2005

A171795(n) = a(-n). a(n+1) * a(n-1) = 6 * a(n)^2. - Michael Somos, Dec 17 2009

More terms from Ryan Propper, Jun 15 2005

A090404 Triangle read by rows in which the n-th row contains the n smallest numbers that are the product of n numbers > 1.

Original entry on oeis.org

2, 4, 6, 8, 12, 16, 16, 24, 32, 36, 32, 48, 64, 72, 80, 64, 96, 128, 144, 160, 192, 128, 192, 256, 288, 320, 384, 432, 256, 384, 512, 576, 640, 768, 864, 896, 512, 768, 1024, 1152, 1280, 1536, 1728, 1792, 1920, 1024, 1536, 2048, 2304, 2560, 3072, 3456, 3584, 3840, 4096, 2048, 3072, 4096, 4608, 5120, 6144, 6912, 7168, 7680, 8192, 9216

Offset: 1

Amarnath Murthy, Apr 02 2003

			Triangle begins:
2
4 6
8 12 16
...

Cf. A081954, A002262.

Corrected and extended by David Wasserman, Jul 21 2004

cp's OEIS Frontend

A081955 a(n) = 2^r*3^s where r = n(n+1)/2 and s = n(n-1)/2.

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