A333937 Triangle read by rows: T(n, k) = (k-1)*n - binomial(n, 2) + floor((n-k)/2) + 1, transposed.

1, 1, 2, 2, 3, 4, 2, 5, 6, 7, 3, 6, 9, 10, 11, 3, 8, 11, 14, 15, 16, 4, 9, 14, 17, 20, 21, 22, 4, 11, 16, 21, 24, 27, 28, 29, 5, 12, 19, 24, 29, 32, 35, 36, 37, 5, 14, 21, 28, 33, 38, 41, 44, 45, 46, 6, 15, 24, 31, 38, 43, 48, 51, 54, 55, 56, 6, 17, 26, 35, 42, 49, 54, 59, 62, 65, 66, 67

Offset

1,3

Links

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

P. Erdős and L. Moser, An extremal problem in graph theory, J. Austral. Math. Soc. 11 (1970), 42--47.

Example

Triangle begins:
1,
1, 2,
2, 3,  4,
2, 5,  6,  7,
3, 6,  9, 10, 11,
3, 8, 11, 14, 15, 16,
4, 9, 14, 17, 20, 21, 22,
...

Prog

(PARI) T(n, k) = (k-1)*n - binomial(n, 2) + (n-k)\2 + 1;
matrix(7, 7, n, k, if (k>n, 0, T(k, n))) \\ to see the triangle

Crossrefs

Sequence in context: A205703 A363100 A367467 * A325785 A207632 A175503

Adjacent sequences: A333934 A333935 A333936 * A333938 A333939 A333940

Keyword

nonn,tabl

Author

Michel Marcus, Apr 11 2020

Status

approved