The On-Line Encyclopedia of Integer Sequences (OEIS)

A131819 revision #4

A131819

A131818 * A000012 as infinite lower triangular matrices. Triangle read by rows, partial sums starting from the right of A131818.

1, 4, 2, 8, 5, 3, 13, 9, 7, 4, 19, 14, 12, 9, 5, 26, 20, 18, 15, 11, 6, 34, 27, 25, 22, 18, 13, 7, 43, 35, 33, 30, 26, 21, 15, 8, 53, 44, 42, 39, 35, 30, 24, 17, 9, 64, 54, 52, 49, 45, 40, 34, 27, 19, 10, 76, 65, 63, 60, 56, 51, 45, 38, 30, 21, 11

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OFFSET

1,2

COMMENTS

Left column = A034856: (1, 4, 8, 13, 19, 26, 34,...). Row sums = A131820: (1, 6, 16, 33, 59, 96,...).

LINKS

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

EXAMPLE

First few rows of the triangle are:

4, 2;

8, 5, 3;

13, 9, 7, 4;

19, 14, 12, 9, 5;

26, 20, 18, 15, 11, 6;

34, 27, 25, 22, 18, 13, 7;

...

PROG

(PARI) tabl(nn) = {m131818 = matrix(nn, nn, n, k, if (k==1, n, if (k <= n, k, 0))); m000012 = matrix(nn, nn, n, k, (k<=n)); m131819 = m131818 * m000012; for (n = 1, nn, for (k = 1, n, print1(m131819[n, k], ", "); ); ); } \\ Michel Marcus, Feb 12 2014

CROSSREFS

Cf. A131818, A000012, A131820, A034856.

Sequence in context: A141073 A261830 A194038 * A194064 A194054 A191536

Adjacent sequences: A131816 A131817 A131818 * A131820 A131821 A131822

KEYWORD

nonn,tabl

AUTHOR

Gary W. Adamson, Jul 18 2007

EXTENSIONS

More terms from Michel Marcus, Feb 12 2014

STATUS

proposed