A080818 Triangle read by rows in which the n-th row contains n distinct numbers whose sum is the smallest square.

1, 1, 3, 1, 2, 6, 1, 2, 3, 10, 1, 2, 3, 4, 6, 1, 2, 3, 4, 5, 10, 1, 2, 3, 4, 5, 6, 15, 1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8, 13, 1, 2, 3, 4, 5, 6, 7, 8, 9, 19, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 26, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 15, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 22, 1, 2, 3, 4, 5, 6, 7, 8

Offset

1,3

Comments

If n(n+1)/2 is a square triangular number then the n-th row contains first n natural numbers (e.g., the 8th row).

Links

Table of n, a(n) for n=1..99.

Example

1; 1,3; 1,2,6; 1,2,3,10; 1,2,3,4,6; 1,2,3,4,5,10; 1,2,3,4,5,6,15; 1,2,3,4,5,6,...

Maple

seq(op([seq(i, i=1..n-1), (ceil(sqrt(n*(n+1)/2)))^2 - n*(n-1)/2]), n=1..15); # C. Ronaldo

Crossrefs

Cf. A080817, A080819, A080820.

Sequence in context: A112571 A051277 A300908 * A334354 A052417 A130509

Adjacent sequences: A080815 A080816 A080817 * A080819 A080820 A080821

Keyword

nonn,tabl

Author

Amarnath Murthy, Mar 21 2003

Extensions

More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Dec 19 2004

Status

approved