login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A180482 Numbers n such that r*n*n/k is an integer. n=(x_1 x_2 ... x_r) where x_i are digits of n, k = x_1^2 + x_2^2 + ... + x_r^2. 0
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 20, 22, 30, 33, 40, 44, 50, 55, 60, 66, 70, 77, 80, 88, 90, 99, 100, 110, 111, 112, 114, 120, 130, 133, 154, 170, 175, 200, 210, 220, 222, 224, 228, 240, 260, 266, 267, 298, 300, 310, 315, 330, 333, 336, 340, 360, 372, 376, 390, 399 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..61.

EXAMPLE

n=715, r=3, 715*715*3/(7*7+1*1+5*5)=20449, n=715 belongs to the sequence.

CROSSREFS

Cf. A005349

Sequence in context: A325152 A061917 A125289 * A193460 A114801 A114802

Adjacent sequences:  A180479 A180480 A180481 * A180483 A180484 A180485

KEYWORD

base,easy,nonn

AUTHOR

Ctibor O. Zizka, Sep 07 2010

STATUS

approved

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 August 4 09:03 EDT 2020. Contains 336201 sequences. (Running on oeis4.)