A247936 Riordan array ((1-2x)/(1-3x), 2x).

1, 1, 2, 3, 2, 4, 9, 6, 4, 8, 27, 18, 12, 8, 16, 81, 54, 36, 24, 16, 32, 243, 162, 108, 72, 48, 32, 64, 729, 486, 324, 216, 144, 96, 64, 128, 2187, 1458, 972, 648, 432, 288, 192, 128, 256, 6561, 4374, 2916, 1944, 1296, 864, 576, 384, 256, 512, 19683, 13122

Offset

0,3

Comments

Mirror of A153279.

Links

Table of n, a(n) for n=0..56.

Formula

Sum_{k, 0<=k<=n} T(n,k) = 3^n = A000244(n).

T(n,k) = A133494(n-k)*2^k.

T(2n,n) = A167747(n).

Example

Triangle begins:
1
1, 2
3, 2, 4
9, 6, 4, 8
27, 18, 12, 8, 16
81, 54, 36, 24, 16, 32
243, 162, 108, 72, 48, 32, 64
Production matrix begins:
1, 2
1, 0, 2
1, 0, 0, 2
1, 0, 0, 0, 2
1, 0, 0, 0, 0, 2
1, 0, 0, 0, 0, 0, 2
1, 0, 0, 0, 0, 0, 0, 2

Crossrefs

Cf. A000079, A000244, A133494, A153279, A167747.

Sequence in context: A059576 A274803 A274749 * A231150 A274858 A207997

Adjacent sequences: A247933 A247934 A247935 * A247937 A247938 A247939

Keyword

nonn,tabl

Author

Philippe Deléham, Sep 26 2014

Status

approved