A194358 Triangle of divisors of 30^n, each number occurring once.

1, 2, 3, 5, 6, 10, 15, 30, 4, 9, 12, 18, 20, 25, 36, 45, 50, 60, 75, 90, 100, 150, 180, 225, 300, 450, 900, 8, 24, 27, 40, 54, 72, 108, 120, 125, 135, 200, 216, 250, 270, 360, 375, 500, 540, 600, 675, 750, 1000, 1080, 1125, 1350, 1500, 1800, 2250, 2700, 3000

Offset: 0

Author

T. D. Noe, Aug 26 2011

Keywords

• nonn
• tabf

Comments

The length of row k is A003215(k), the centered hexagonal numbers, 3k^2 + 3k + 1.

Examples

			The triangle has rows beginning with 2^k and ending with 30^k:
1
2, 3, 5, 6, 10, 15, 30
4, 9, 12, 18, 20, 25, 36, 45, 50, 60, 75, 90, 100, 150, 180, 225, 300, 450, 900
		

Links

• T. D. Noe, Table of n, a(n) for n=0..9260 (rows 0..20)

Crossrefs

Cf. A194356, A194357.

Cf. A051037 (5-smooth numbers).

Programs

Mathematica

Join[{{1}}, Table[Complement[Divisors[30^n], Divisors[30^(n-1)]], {n, 9}]]