A134482 Triangle read by rows: row n consists of n followed by the numbers n through 2n-2.

1, 2, 2, 3, 3, 4, 4, 4, 5, 6, 5, 5, 6, 7, 8, 6, 6, 7, 8, 9, 10, 7, 7, 8, 9, 10, 11, 12, 8, 8, 9, 10, 11, 12, 13, 14, 9, 9, 10, 11, 12, 13, 14, 15, 16, 10, 10, 11, 12, 13, 14, 15, 16, 17, 18, 11, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 12, 12, 13, 14, 15, 16

Offset

1,2

Comments

Row sums = A005448.

Links

Table of n, a(n) for n=1..72.

Formula

T(n,1)=n, T(n,k)=n+k-2 for 2<=k<=n. G.f.=z(1-2tz+2zt^2-t^3*z^3)/[(1-z)(1-tz)]^2. - Emeric Deutsch, Nov 24 2007

Example

First few rows of the triangle are:
1;
2, 2;
3, 3, 4;
4, 4, 5, 6;
5, 5, 6, 7, 8;
6, 6, 7, 8, 9, 10;
7, 7, 8, 9, 10, 11, 12;
...

Maple

T:=proc(n, k) if n<k then 0 elif k=1 then n else n+k-2 end if end proc: for n to 10 do seq(T(n, k), k=1..n) end do; # yields sequence in triangular form - Emeric Deutsch, Nov 24 2007

Mathematica

Flatten[Table[Join[{n}, Range[n, 2n-2]], {n, 12}]] (* Harvey P. Dale, Jun 18 2013 *)

Crossrefs

Cf. A005448.

Sequence in context: A050506 A155213 A029122 * A132921 A255232 A181988

Adjacent sequences: A134479 A134480 A134481 * A134483 A134484 A134485

Keyword

nonn,tabl

Author

Gary W. Adamson, Oct 27 2007

Extensions

Corrected and extended by Harvey P. Dale, Jun 18 2013

Status

approved