A038327 - OEIS

A038327

Triangle whose (i,j)-th entry is binomial(i,j)*12^(i-j)*1^j.

1, 12, 1, 144, 24, 1, 1728, 432, 36, 1, 20736, 6912, 864, 48, 1, 248832, 103680, 17280, 1440, 60, 1, 2985984, 1492992, 311040, 34560, 2160, 72, 1, 35831808, 20901888, 5225472, 725760, 60480, 3024, 84, 1, 429981696, 286654464, 83607552

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OFFSET

0,2

COMMENTS

T(i,j) is the number of i-permutations of 13 objects a,b,c,d,e,f,g,h,i,j,k,l,m, with repetition allowed, containing j a's. - Zerinvary Lajos, Dec 21 2007

These are the rows of A013619 read right to left. Row sums are A001022(i). - R. J. Mathar, Mar 05 2008

REFERENCES

B. N. Cyvin et al., Isomer enumeration of unbranched catacondensed polygonal systems with pentagons and heptagons, Match, No. 34 (Oct 1996), pp. 109-121.

LINKS

Table of n, a(n) for n=0..38.

EXAMPLE

12, 1

144, 24, 1

1728, 432, 36, 1

20736, 6912, 864, 48, 1

248832, 103680, 17280, 1440, 60, 1

2985984, 1492992, 311040, 34560, 2160, 72, 1

35831808, 20901888, 5225472, 725760, 60480, 3024, 84, 1

MAPLE

for i from 0 to 7 do seq(binomial(i, j)*12^(i-j), j = 0 .. i) od; # Zerinvary Lajos, Dec 21 2007