A038257 Triangle whose (i,j)-th entry is binomial(i,j)*6^(i-j)*3^j.

1, 6, 3, 36, 36, 9, 216, 324, 162, 27, 1296, 2592, 1944, 648, 81, 7776, 19440, 19440, 9720, 2430, 243, 46656, 139968, 174960, 116640, 43740, 8748, 729, 279936, 979776, 1469664, 1224720, 612360, 183708, 30618, 2187, 1679616

Offset

0,2

Links

Table of n, a(n) for n=0..36.

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

G.f.: 1/(1 - 6*x - 3*x*y). - Ilya Gutkovskiy, Apr 21 2017

Crossrefs

Sequence in context: A163913 A022666 A202363 * A090138 A229130 A349492

Adjacent sequences: A038254 A038255 A038256 * A038258 A038259 A038260

Keyword

nonn,tabl,easy

Author

N. J. A. Sloane.

Status

approved