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A129765 Triangle, (1, 1, 2, 2, 2,...) in every column. 2
1, 1, 1, 2, 1, 1, 2, 2, 1, 1, 2, 2, 2, 1, 1, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Row sums = A004277, (1, 2, 4, 6, 8, 10,...). Binomial transform of (1, 1, 2, 2, 2...) = A000325, starting (1, 2, 5, 12, 27, 58,...). Binomial transform of A130196 = A130197, a triangle with row sums = the Cullen numbers, A002064.

LINKS

Table of n, a(n) for n=1..105.

FORMULA

Triangle, (1, 1, 2, 2, 2,...) in every column. By rows, (1; 1, 1; 2, 1, 1;...), continuing with (n-2) 2's followed by two 1's. Inverse of A000012 as an infinite lower triangular matrix (all 1's and the rest zeros), signed by columns: (+ - - + + - -,...).

EXAMPLE

First few rows of the triangle are:

1;

1, 1;

2, 1, 1;

2, 2, 1, 1;

2, 2, 2, 1, 1;

...

MAPLE

A129765 := proc(n, m) if abs(n-m)<2 then 1 ; else 2 ; fi ; end: for n from 1 to 18 do for m from 1 to n do printf("%d, ", A129765(n, m)) ; od ; od ; # R. J. Mathar, Jun 08 2007

CROSSREFS

Cf. A004277, A002064, A000325, A130197.

Sequence in context: A174886 A157415 A154325 * A143187 A143209 A163994

Adjacent sequences:  A129762 A129763 A129764 * A129766 A129767 A129768

KEYWORD

nonn,tabl,easy

AUTHOR

Gary W. Adamson, May 16 2007

EXTENSIONS

More terms from R. J. Mathar, Jun 08 2007

STATUS

approved

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Last modified November 18 07:01 EST 2018. Contains 317279 sequences. (Running on oeis4.)