1,2

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

Triangle read by rows, A000012 * A145677 * A000012; where A000012 = an infinite lower triangular matrix: (1; 1,1; 1,1,1;...), with all 1's.

First few rows of the triangle =

1;

3, 1;

6, 3, 2;

10, 6, 5, 3;

15, 10, 9, 7, 4;

21, 15, 14, 12, 9, 5;

28, 21, 10, 18, 15, 11, 6;

36, 28, 27, 25, 22, 18, 13, 7;

45, 36, 35, 33, 30, 26, 21, 15, 8;

55, 45, 44, 42, 39, 35, 30, 24, 17, 9;

66, 55, 54, 52, 49, 45, 40, 34, 27, 19, 10;

78, 66, 65, 63, 60, 56, 51, 45, 38, 30, 21, 11;

91, 78, 77, 75, 72, 68, 63, 57, 50, 42, 33, 23, 12;

...

Cf. A145677, A006527 (row sums).

Sequence in context: A107884 A185628 A321194 * A226132 A121443 A008795

Adjacent sequences: A158819 A158820 A158821 * A158823 A158824 A158825

nonn,tabl

Gary W. Adamson & Roger L. Bagula, Mar 28 2009

Definition corrected by Michael Somos, Nov 05 2011

approved