A143971 - OEIS

A143971

Triangle read by rows, (3n-2) subsequences decrescendo

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

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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

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 * A367898 A016688 A143972

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