A162610 Triangle read by rows in which row n lists n terms, starting with 2n-1, with gaps = n-1 between successive terms.

1, 3, 4, 5, 7, 9, 7, 10, 13, 16, 9, 13, 17, 21, 25, 11, 16, 21, 26, 31, 36, 13, 19, 25, 31, 37, 43, 49, 15, 22, 29, 36, 43, 50, 57, 64, 17, 25, 33, 41, 49, 57, 65, 73, 81, 19, 28, 37, 46, 55, 64, 73, 82, 91, 100, 21, 31, 41, 51, 61, 71, 81, 91, 101, 111, 121

Offset: 1

Author

Omar E. Pol, Jul 09 2009

Keywords

• easy
• tabl
• nonn

Comments

Note that the last term of the n-th row is the n-th square A000290(n).

Row sums are n*(n^2+2*n-1)/2, apparently in A127736. - R. J. Mathar, Jul 20 2009

Examples

			Triangle begins:
1
3, 4
5, 7, 9
7, 10, 13, 16
9, 13, 17, 21, 25
11, 16, 21, 26, 31, 36
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000027, A000290, A159797, A159798.

Cf. A209297; A005408 (left edge), A000290 (right edge), A127736 (row sums), A056220 (central terms), A026741 (number of odd terms per row), A142150 (number of even terms per row), A221491 (number of primes per row).

Programs

Haskell

a162610 n k = k * n - k + n
a162610_row n = map (a162610 n) [1..n]
a162610_tabl = map a162610_row [1..]
-- Reinhard Zumkeller, Jan 19 2013

Mathematica

Flatten[Table[NestList[#+n-1&,2n-1,n-1], {n,15}]] (* Harvey P. Dale, Oct 20 2011 *)

Python

# From R. J. Mathar, Oct 20 2009
def A162610(n, k):
    return 2*n-1+(k-1)*(n-1)
print([A162610(n,k) for n in range(1,20) for k in range(1,n+1)])

Formula

T(n,k) = n+k*n-k, 1<=k<=n. - R. J. Mathar, Oct 20 2009

T(n,k) = (k+1)*(n-1)+1. - Reinhard Zumkeller, Jan 19 2013

Extensions

More terms from R. J. Mathar, Oct 20 2009