A127420 Triangle, read by rows, where row n+1 is generated from row n by first inserting zeros at positions {(m+2)*(m+3)/2, m>=0} in row n and then taking the partial sums in reverse order, for n>=2, starting with 1's in the initial two rows.

1, 1, 1, 2, 1, 1, 4, 2, 2, 1, 9, 5, 5, 3, 1, 1, 24, 15, 15, 10, 5, 5, 2, 1, 77, 53, 53, 38, 23, 23, 13, 8, 3, 3, 1, 295, 218, 218, 165, 112, 112, 74, 51, 28, 28, 15, 7, 4, 1, 1, 1329, 1034, 1034, 816, 598, 598, 433, 321, 209, 209, 135, 84, 56, 28, 28, 13, 6, 2, 1, 6934, 5605

Offset: 0

Author

Paul D. Hanna, Jan 14 2007

Keywords

• nonn
• tabf

Comments

Column 0 forms A091352, which also equals column 1 of table A125781, where table A125781 is generated by a complementary recurrence of this triangle. The number of terms in row n is A127419(n).

Examples

			To generate row 6, start with row 5:
24, 15, 15, 10, 5, 5, 2, 1;
insert zeros at positions [1,4,8,13,..., (m+2)*(m+3)/2 - 2,...]:
24, 0, 15, 15, 0, 10, 5, 5, 0, 2, 1;
then row 6 equals the partial sums of row 5 taken in reverse order:
24, _0, 15, 15, _0, 10, _5, 5, 0, 2, 1;
77, 53, 53, 38, 23, 23, 13, 8, 3, 3, 1.
Triangle begins:
1;
1, 1;
2, 1, 1;
4, 2, 2, 1;
9, 5, 5, 3, 1, 1;
24, 15, 15, 10, 5, 5, 2, 1;
77, 53, 53, 38, 23, 23, 13, 8, 3, 3, 1;
295, 218, 218, 165, 112, 112, 74, 51, 28, 28, 15, 7, 4, 1, 1;
1329, 1034, 1034, 816, 598, 598, 433, 321, 209, 209, 135, 84, 56, 28, 28, 13, 6, 2, 1;
Column 0 of this triangle equals column 1 of triangle A091351, where triangle A091351 begins:
1;
1, 1;
1, 2, 1;
1, 4, 3, 1;
1, 9, 9, 4, 1;
1, 24, 30, 16, 5, 1;
1, 77, 115, 70, 25, 6, 1;
1, 295, 510, 344, 135, 36, 7, 1; ...
and column k of A091351 = row sums of matrix power A091351^k for k>=0.
		

Crossrefs

Cf. A091352, A091351, A125781, A127419.