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A257620 Triangle read by rows: T(n,k) = t(n-k, k); t(n,m) = f(m)*t(n-1,m) + f(n)*t(n,m-1), where f(x) = 3*x + 3. 11
1, 3, 3, 9, 36, 9, 27, 297, 297, 27, 81, 2106, 5346, 2106, 81, 243, 13851, 73386, 73386, 13851, 243, 729, 87480, 868239, 1761264, 868239, 87480, 729, 2187, 540189, 9388791, 34158753, 34158753, 9388791, 540189, 2187, 6561, 3293622, 95843088, 578903274, 1024762590, 578903274, 95843088, 3293622, 6561 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Row sums are: 1, 6, 54, 648, 9720, 174960, 3674160, 88179840, 2380855680, 71425670400, 2357047123200, ... (see A034001).

LINKS

Table of n, a(n) for n=0..44.

FORMULA

T(n,k) = t(n-k, k); t(0,0) = 1, t(n,m) = 0 if n < 0 or m < 0, else t(n,m) = f(m)*t(n-1,m) + f(n)*t(n,m-1), where f(x) = 3*x + 3.

EXAMPLE

1

3 3

9 36 9

27 297 297 27

81 2106 5346 2106 81

243 13851 73386 73386 13851 243

729 87480 868239 1761264 868239 87480 729

2187 540189 9388791 34158753 34158753 9388791 540189 2187

6561 3293622 95843088 578903274 1024762590 578903274 95843088 3293622 6561

CROSSREFS

Cf. A142458, A257610, A257622, A257624, A257626.

Cf. A038221, A257180, A257611, A257621, A257623, A257625, A257627.

Similar sequences listed in A256890.

Sequence in context: A268617 A264412 A202889 * A032086 A241278 A100239

Adjacent sequences:  A257617 A257618 A257619 * A257621 A257622 A257623

KEYWORD

nonn,tabl

AUTHOR

Dale Gerdemann, May 09 2015

STATUS

approved

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Last modified February 27 09:20 EST 2020. Contains 332301 sequences. (Running on oeis4.)