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A129994 Triangle read by rows: A007318^(-1) * A131109, or equally 2*A007318 - I. 1
1, 2, 1, 2, 4, 1, 2, 6, 6, 1, 2, 8, 12, 8, 1, 2, 10, 20, 20, 10, 1, 2, 12, 30, 40, 30, 12, 1, 2, 14, 42, 70, 70, 42, 14, 1, 2, 16, 56, 112, 140, 112, 56, 16, 1, 2, 18, 72, 168, 252, 252, 168, 72, 18, 1 (list; table; graph; refs; listen; history; internal format)
OFFSET

0,2

COMMENTS

Row sums = (1, 3, 7, 15, 31,...).

FORMULA

Inverse binomial transform of triangle A131109. Let Pascal's triangle A007318 = P, then this is (1/P) * (2P^2 - P) = 2*P - I, I = Identity matrix.

EXAMPLE

First few rows of the triangle are:

1;

2, 1;

2, 4, 1;

2, 6, 6, 1;

2, 8, 12, 8, 1;

2, 10, 20, 20, 10, 1;

2, 12, 30, 40, 30, 12, 1;

...

CROSSREFS

Cf. A131109, A007318.

Sequence in context: A035015 A203647 A114791 * A080246 A113413 A125694

Adjacent sequences:  A129991 A129992 A129993 * A129995 A129996 A129997

KEYWORD

nonn,tabl

AUTHOR

Gary W. Adamson (qntmpkt(AT)yahoo.com), Jun 15 2007

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Last modified February 15 14:57 EST 2012. Contains 205823 sequences.