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A143971 Triangle read by rows, (3n-2) subsequences decrescendo 2
1, 4, 1, 7, 4, 1, 10, 7, 4, 1, 13, 10, 7, 4, 1, 16, 13, 10, 7, 4, 1, 19, 16, 13, 10, 7, 4, 1, 22, 19, 16, 13, 10, 7, 4, 1, 25, 22, 19, 16, 13, 10, 7, 4, 1, 28, 25, 22, 19, 16, 13, 10, 7, 4, 1, 31, 28, 25, 22, 19, 16, 13, 10, 7, 4, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Row sums = pentagonal numbers, A000326: (1, 5, 12, 22, 35,...).

The alternating row sums lead to A032766 and the antidiagonal sums to A006578.  - Johannes W. Meijer, Sep 05 2013

LINKS

Table of n, a(n) for n=1..66.

FORMULA

Triangle read by rows, (3n-2) subsequences decrescendo; 1<=k<=n.

(1, 4, 7, 10, 13,...) in every column.

T(n,k) = 3*n - 3*k + 1.

EXAMPLE

Triangle starts

1;

4, 1;

7, 4, 1;

10, 7, 4, 1;

...

MAPLE

T := (n, k) -> 3*n-3*k+1: seq(seq(T(n, k), k=1..n), n=1..11); # Johannes W. Meijer, Sep 05 2013

CROSSREFS

Cf. A016777, A000326, A209634.

Sequence in context: A335619 A037022 A037023 * A016688 A143972 A019651

Adjacent sequences:  A143968 A143969 A143970 * A143972 A143973 A143974

KEYWORD

nonn,tabl

AUTHOR

Gary W. Adamson, Sep 06 2008

EXTENSIONS

Terms a(17) and a(38) corrected and terms added by Johannes W. Meijer, Sep 05 2013

STATUS

approved

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Last modified April 22 21:05 EDT 2021. Contains 343177 sequences. (Running on oeis4.)