login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A194358 Triangle of divisors of 30^n, each number occurring once. 5

%I

%S 1,2,3,5,6,10,15,30,4,9,12,18,20,25,36,45,50,60,75,90,100,150,180,225,

%T 300,450,900,8,24,27,40,54,72,108,120,125,135,200,216,250,270,360,375,

%U 500,540,600,675,750,1000,1080,1125,1350,1500,1800,2250,2700,3000

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

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

%H T. D. Noe, <a href="/A194358/b194358.txt">Table of n, a(n) for n=0..9260 (rows 0..20)</a>

%e The triangle has rows beginning with 2^k and ending with 30^k:

%e 1

%e 2, 3, 5, 6, 10, 15, 30

%e 4, 9, 12, 18, 20, 25, 36, 45, 50, 60, 75, 90, 100, 150, 180, 225, 300, 450, 900

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

%Y Cf. A194356, A194357.

%Y Cf. A051037 (5-smooth numbers).

%K nonn,tabf

%O 0,2

%A _T. D. Noe_, Aug 26 2011

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 19 08:23 EDT 2019. Contains 325155 sequences. (Running on oeis4.)