A284359 Double triangle (2*n+2 terms by row). Every row is 2*n + 1 followed by 2*n + 1 times 2*n + 2.

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

Offset: 0

Author

Paul Curtz, Mar 25 2017

Keywords

• nonn
• tabf

Comments

In essence the same as A167991. - R. J. Mathar, Mar 27 2017

Examples

			1,  2,
3,  4,  4,  4,
5,  6,  6,  6,  6,  6,
7,  8,  8,  8,  8,  8,  8,  8,
9, 10, 10, 10, 10, 10, 10, 10, 10, 10,
... .
The row sum is A000466(n+1).
		

Crossrefs

Cf. A000466, A005408, A103517 (main diagonal), A167381.

Programs

Mathematica

Table[2 n + 2 - Boole[k == 1], {n, 0, 8}, {k, 2 n + 2}] // Flatten (* Michael De Vlieger, Mar 25 2017 *)

PARI

for(n=0, 10, for(k=1, 2*n + 2, print1(2*n + 2 - (k==1), ", ");); print();) \\ Indranil Ghosh, Mar 26 2017, translated from Mathematica code

Python

for n in range(0, 11):
    print([2*n + 2 -(k==1) for k in range(1, 2*n + 3)])
# Indranil Ghosh, Mar 26 2017

Formula

a(n) = A167381(n+1) - A167381(n).