|
|
A134483
|
|
Triangle read by rows: T(n,k) = 2n + k - 2; 1 <= k <= n.
|
|
2
|
|
|
1, 3, 4, 5, 6, 7, 7, 8, 9, 10, 9, 10, 11, 12, 13, 11, 12, 13, 14, 15, 16, 13, 14, 15, 16, 17, 18, 19, 15, 16, 17, 18, 19, 20, 21, 22, 17, 18, 19, 20, 21, 22, 23, 24, 25, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28
(list;
table;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
Row sums are the heptagonal numbers, A000566: (1, 7, 18, 34, 55, 81, ...).
Row n consists of n consecutive integers starting with 2n-1. - Emeric Deutsch, Nov 04 2007
|
|
LINKS
|
|
|
FORMULA
|
T(n,k) = 2n + k - 2 for 1 <= k <= n.
G.f. = t*z(1 + z + 2*t*z - 4*t*z^2)/((1-z)^2*(1-t*z)^2). (End)
a(n) = j+2*t, where j = n - t*(t+1)/2, t = floor((-1+sqrt(8*n-7))/2). (End)
|
|
EXAMPLE
|
First few rows of the triangle:
1;
3, 4;
5, 6, 7;
7, 8, 9, 10;
9, 10, 11, 12, 13;
...
|
|
MAPLE
|
for n to 10 do seq(2*n+k-2, k=1..n) end do; # yields sequence in triangular form - Emeric Deutsch, Nov 04 2007
|
|
MATHEMATICA
|
Table[2n+k-2, {n, 10}, {k, n}]//Flatten (* Harvey P. Dale, Oct 14 2022 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|