A081956 -id:A081956 - 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

A081954 Triangle read by rows: T(n, k) = 2^(n-k)*3^k, n >= 1, 0 <= k < n.

Original entry on oeis.org

2, 4, 6, 8, 12, 18, 16, 24, 36, 54, 32, 48, 72, 108, 162, 64, 96, 144, 216, 324, 486, 128, 192, 288, 432, 648, 972, 1458, 256, 384, 576, 864, 1296, 1944, 2916, 4374, 512, 768, 1152, 1728, 2592, 3888, 5832, 8748, 13122, 1024, 1536, 2304, 3456, 5184, 7776

Offset: 1

Amarnath Murthy, Apr 02 2003

			Triangle begins:
2
4 6
8 12 18
16 24 36 54
32 48 72 108 162
...

Leading diagonal is given by A025192.

Cf. A025192, A081955, A081956, A002262, A090404.

tabl(nrows) = {for (n=1, nrows, for (k=0, n-1, print1(2^(n-k)*3^k, ", ");); print(););} \\ Michel Marcus, May 14 2013

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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