



1, 4, 3, 7, 6, 3, 10, 9, 8, 7, 13, 12, 11, 10, 9, 16, 15, 14, 13, 12, 11, 19, 18, 17, 16, 15, 14, 13, 22, 21, 10, 19, 18, 17, 16, 15, 25, 24, 23, 22, 21, 20, 19, 18, 17, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19
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OFFSET

0,2


COMMENTS

Row sums = A000566, the heptagonal numbers: (1, 7, 18, 34, 55,...).


LINKS

Table of n, a(n) for n=0..54.


FORMULA

A002024 + A128076  A000012 as infinite lower triangular matrices. By rows, (n+1) terms of 3n+1, 3n, 3n1,...


EXAMPLE

First few rows of the triangle are:
1;
4, 3;
7, 6, 5;
10, 9, 8, 7;
13, 12, 11, 10, 9;
16, 15, 14, 13, 12, 11;
19, 18, 17, 16, 15, 14, 13;
...


CROSSREFS

Cf. A128076, A002024, A000566.
Sequence in context: A093051 A089020 A046560 * A205392 A249189 A168200
Adjacent sequences: A131410 A131411 A131412 * A131414 A131415 A131416


KEYWORD

nonn,tabl


AUTHOR

Gary W. Adamson, Jul 08 2007


STATUS

approved



