A331152 Triangle read by rows: T(n,k) (n>=k>=1) = f(n,n-k+1) where f(n,k) = ceiling((n/k)*floor(n/k)).

1, 1, 4, 1, 2, 9, 1, 2, 4, 16, 1, 2, 2, 5, 25, 1, 2, 2, 4, 9, 36, 1, 2, 2, 2, 5, 11, 49, 1, 2, 2, 2, 4, 6, 16, 64, 1, 2, 2, 2, 2, 5, 9, 18, 81, 1, 2, 2, 2, 2, 4, 5, 10, 25, 100, 1, 2, 2, 2, 2, 2, 5, 6, 11, 28, 121, 1, 2, 2, 2, 2, 2, 4, 5, 9, 16, 36, 144, 1, 2, 2, 2, 2, 2, 2, 5, 6, 10, 18, 39, 169

Offset

1,3

Links

Table of n, a(n) for n=1..91.

Robert J. McEliece and Herbert Taylor, Covering tori with squares, Journal of Combinatorial Theory, Series A 14.1 (1973): 119-124.

Example

Triangle begins:
1,
1, 4,
1, 2, 9,
1, 2, 4, 16,
1, 2, 2, 5, 25,
1, 2, 2, 4, 9, 36,
1, 2, 2, 2, 5, 11, 49,
1, 2, 2, 2, 4, 6, 16, 64,
1, 2, 2, 2, 2, 5, 9, 18, 81,
1, 2, 2, 2, 2, 4, 5, 10, 25, 100,
1, 2, 2, 2, 2, 2, 5, 6, 11, 28, 121,
1, 2, 2, 2, 2, 2, 4, 5, 9, 16, 36, 144,
1, 2, 2, 2, 2, 2, 2, 5, 6, 10, 18, 39, 169,
...

Crossrefs

Cf. A331145-A331154.

Sequence in context: A004160 A128077 A128078 * A264922 A341030 A233528

Adjacent sequences: A331149 A331150 A331151 * A331153 A331154 A331155

Keyword

nonn,tabl

Author

N. J. A. Sloane, Jan 14 2020

Status

approved