This site is supported by donations to The OEIS Foundation.

"Email this user" was broken Aug 14 to 9am Aug 16. If you sent someone a message in this period, please send it again.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A038220 Triangle whose (i,j)-th entry is binomial(i,j)*3^(i-j)*2^j. 6
 1, 3, 2, 9, 12, 4, 27, 54, 36, 8, 81, 216, 216, 96, 16, 243, 810, 1080, 720, 240, 32, 729, 2916, 4860, 4320, 2160, 576, 64, 2187, 10206, 20412, 22680, 15120, 6048, 1344, 128, 6561, 34992, 81648, 108864, 90720, 48384, 16128, 3072, 256 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Row sums give A000351; central terms give A119309. - Reinhard Zumkeller, May 14 2006 LINKS Reinhard Zumkeller, Rows n = 0..125 of triangle, flattened B. N. Cyvin et al., Isomer enumeration of unbranched catacondensed polygonal systems with pentagons and heptagons, Match, No. 34 (Oct 1996), pp. 109-121. FORMULA T(n,k) = A007318(n,k) * A036561(n,k). - Reinhard Zumkeller, May 14 2006 G.f.: 1/(1 - 3*x - 2*x*y). - Ilya Gutkovskiy, Apr 21 2017 PROG (Haskell) a038220 n k = a038220_tabl !! n !! k a038220_row n = a038220_tabl !! n a038220_tabl = iterate (\row ->    zipWith (+) (map (* 3) (row ++ [0])) (map (* 2) ([0] ++ row))) [1] -- Reinhard Zumkeller, May 26 2013, Apr 02 2011 (PARI) T(i, j)=binomial(i, j)*3^(i-j)*2^j \\ Charles R Greathouse IV, Jul 19 2016 CROSSREFS Cf. A013620, A000079, A000244, A013613, A038221. Sequence in context: A246788 A099887 A274827 * A053151 A053088 A077898 Adjacent sequences:  A038217 A038218 A038219 * A038221 A038222 A038223 KEYWORD nonn,tabl,easy AUTHOR STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.