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A194358 Triangle of divisors of 30^n, each number occurring once. 5
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

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

LINKS

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

EXAMPLE

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

MATHEMATICA

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

CROSSREFS

Cf. A194356, A194357.

Cf. A051037 (5-smooth numbers).

Sequence in context: A018305 A018693 A018255 * A018727 A161715 A164523

Adjacent sequences:  A194355 A194356 A194357 * A194359 A194360 A194361

KEYWORD

nonn,tabf

AUTHOR

T. D. Noe, Aug 26 2011

STATUS

approved

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Last modified June 15 20:50 EDT 2019. Contains 324145 sequences. (Running on oeis4.)