A049790 - OEIS

A049790

Triangular array T read by rows: T(n,k) = Sum_{j=1..k} floor(n/floor(k/j)).

1, 2, 3, 3, 4, 7, 4, 6, 9, 11, 5, 7, 11, 13, 18, 6, 9, 14, 16, 22, 24, 7, 10, 16, 18, 25, 27, 34, 8, 12, 18, 22, 29, 31, 39, 43, 9, 13, 21, 24, 32, 35, 44, 47, 55, 10, 15, 23, 27, 37, 39, 49, 53, 61, 66, 11, 16, 25, 29, 40, 42, 53, 57, 66, 71, 82, 12, 18, 28, 33, 44, 48, 59, 64, 74, 79, 91, 94

(list; table; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

G. C. Greubel, Rows n = 1..100 of triangle, flattened

EXAMPLE

Triangle begins as:

2, 3;

3, 4, 7;

4, 6, 9, 11;

5, 7, 11, 13, 18;

6, 9, 14, 16, 22, 24;

7, 10, 16, 18, 25, 27, 34;

8, 12, 18, 22, 29, 31, 39, 43;

MAPLE

seq(seq( add(floor(n/floor(k/j)), j=1..k), k=1..n), n=1..15); # G. C. Greubel, Dec 09 2019

MATHEMATICA

Table[Sum[Floor[n/Floor[k/j]], {j, k}], {n, 15}, {k, n}]//Flatten (* G. C. Greubel, Dec 09 2019 *)

PROG

(PARI) T(n, k) = sum(j=1, k, n\(k\j));

for(n=1, 15, for(k=1, n, print1(T(n, k), ", "))) \\ G. C. Greubel, Dec 09 2019

(Magma) [(&+[Floor(n/Floor(k/j)): j in [1..k]]): k in [1..n], n in [1..15]]; // G. C. Greubel, Dec 09 2019

(Sage) [[sum(floor(n/floor(k/j)) for j in (1..k)) for k in (1..n)] for n in (1..15)] # G. C. Greubel, Dec 09 2019

(GAP) Flat(List([1..15], n-> List([1..n], k-> Sum([1..k], j-> Int(n/Int(k/j)) )))); # G. C. Greubel, Dec 09 2019

CROSSREFS

Cf. A049791, A049792, A049793, A049794, A049795, A049796.

Sequence in context: A266428 A180985 A227385 * A222188 A368307 A368305

Adjacent sequences: A049787 A049788 A049789 * A049791 A049792 A049793

KEYWORD

nonn,tabl

AUTHOR

Clark Kimberling

STATUS

approved