

A143971


Triangle read by rows, (3n2) 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
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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, (3n2) 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*n3*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



