|
|
A100461
|
|
Triangle read by rows, based on array described below.
|
|
7
|
|
|
1, 1, 2, 1, 2, 4, 3, 4, 6, 8, 7, 8, 9, 12, 16, 25, 26, 27, 28, 30, 32, 49, 50, 51, 52, 55, 60, 64, 109, 110, 111, 112, 115, 120, 126, 128, 229, 230, 231, 232, 235, 240, 245, 248, 256, 481, 482, 483, 484, 485, 486, 490, 496, 504, 512, 1003, 1004, 1005, 1008, 1010, 1014, 1015, 1016, 1017, 1020, 1024
(list;
table;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,3
|
|
LINKS
|
|
|
FORMULA
|
Form an array t(m,n) (n >= 1, 1 <= m <= n) by: t(1,n) = 2^(n-1) for all n; t(m+1,n) = (n-m)*floor( (t(m,n) - 1)/(n-m) ) for 1 <= m <= n-1.
|
|
EXAMPLE
|
Array begins:
1 2 4 8 16 32 ...
* 1 2 6 12 30 ...
* * 1 4 9 28 ...
* * * 3 8 27 ...
* * * * 7 26 ...
* * * * * 25 ...
and triangle begins:
1;
1, 2;
1, 2, 4;
3, 4, 6, 8;
7, 8, 9, 12, 16;
25, 26, 27, 28, 30, 32;
49, 50, 51, 52, 55, 60, 64;
109, 110, 111, 112, 115, 120, 126, 128;
|
|
MATHEMATICA
|
t[n_, k_]:= t[n, k]= If[k==1, 2^(n-1), (n-k+1)*Floor[(t[n, k-1] -1)/(n-k+1)]];
Table[t[n, n-k+1], {n, 15}, {k, n}]//Flatten (* G. C. Greubel, Apr 07 2023 *)
|
|
PROG
|
(Magma)
if k eq 1 then return 2^(n-1);
else return (n-k+1)*Floor((t(n, k-1) -1)/(n-k+1));
end if;
end function;
[t(n, n-k+1): k in [1..n], n in [1..12]]; // G. C. Greubel, Apr 07 2023
(SageMath)
if (k==1): return 2^(n-1)
else: return (n-k+1)*((t(n, k-1) -1)//(n-k+1))
flatten([[t(n, n-k+1) for k in range(1, n+1)] for n in range(1, 16)]) # G. C. Greubel, Apr 07 2023
|
|
CROSSREFS
|
|
|
KEYWORD
|
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|