



1, 2, 1, 4, 2, 1, 6, 4, 2, 1, 9, 6, 4, 2, 1, 12, 9, 6, 4, 2, 1, 16, 12, 9, 6, 4, 2, 1, 20, 16, 12, 9, 6, 4, 2, 1, 25, 20, 16, 12, 9, 6, 4, 2, 1, 30, 25, 20, 16, 12, 9, 6, 4, 2, 1, 36, 30, 25, 20, 16, 12, 9, 6, 4, 2, 1, 42, 36, 30, 25, 20, 16, 12, 9, 6, 4, 2, 1
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OFFSET

1,2


COMMENTS

nth row has n nonzero terms of A002620: (1, 2, 4, 6, 9, 12, 16, ...) in reverse.
Row sums = A002623: (1, 3, 7, 13, 22, 34, 50, ...).


LINKS

Table of n, a(n) for n=1..78.


EXAMPLE

First few rows of the triangle are:
1;
2, 1;
4, 2, 1;
6, 4, 2, 1;
9, 6, 4, 2, 1;
12, 9, 6, 4, 2, 1;
...


PROG

(PARI) lista(nn) = {t128174 = matrix(nn, nn, n, k, (k<=n)*(1+(1)^(nk))/2); t004736 = matrix(nn, nn, n, k, (k<=n)*(n  k + 1)); t128177 = t128174*t004736; for (n = 1, nn, for (k = 1, n, print1(t128177[n, k], ", "); ); ); } \\ Michel Marcus, Feb 11 2014


CROSSREFS

Cf. A128174, A004736, A002623, A002620.
Sequence in context: A347069 A325309 A211956 * A087738 A133113 A124840
Adjacent sequences: A128174 A128175 A128176 * A128178 A128179 A128180


KEYWORD

nonn,tabl


AUTHOR

Gary W. Adamson, Feb 17 2007


EXTENSIONS

Partially edited and more terms from Michel Marcus, Feb 11 2014


STATUS

approved



