|
|
A027384
|
|
Number of distinct products i*j with 0 <= i, j <= n.
|
|
11
|
|
|
1, 2, 4, 7, 10, 15, 19, 26, 31, 37, 43, 54, 60, 73, 81, 90, 98, 115, 124, 143, 153, 165, 177, 200, 210, 226, 240, 255, 268, 297, 309, 340, 355, 373, 391, 411, 424, 461, 481, 502, 518, 559, 576, 619, 639, 660, 684, 731, 748, 779, 801, 828, 851, 904, 926, 957, 979, 1009, 1039
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,2
|
|
COMMENTS
|
|
|
LINKS
|
|
|
FORMULA
|
|
|
MAPLE
|
local L, i, j ;
L := {};
for i from 0 to n do
for j from i to n do
L := L union {i*j};
end do:
end do:
nops(L);
|
|
MATHEMATICA
|
u = {}; Table[u = Union[u, n*Range[0, n]]; Length[u], {n, 0, 100}] (* T. D. Noe, Jan 07 2012 *)
|
|
PROG
|
(Haskell)
import Data.List (nub)
a027384 n = length $ nub [i*j | i <- [0..n], j <- [0..n]]
(PARI) a(n) = {my(s=Set()); for (i=0, n, s = setunion(s, Set(vector(n+1, k, i*(k-1)))); ); #s; } \\ Michel Marcus, Jan 01 2019
(Python)
def A027384(n): return len({i*j for i in range(1, n+1) for j in range(1, i+1)})+1 # Chai Wah Wu, Oct 13 2023
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
Fred Schwab (fschwab(AT)nrao.edu)
|
|
STATUS
|
approved
|
|
|
|