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

 

Logo

Invitation: celebrating 50 years of OEIS, 250000 sequences, and Sloane's 75th, there will be a conference at DIMACS, Rutgers, Oct 9-10 2014.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A020342 Vampire numbers (definition 1): n has a nontrivial factorization using n's digits. 12
126, 153, 688, 1206, 1255, 1260, 1395, 1435, 1503, 1530, 1827, 2187, 3159, 3784, 6880, 10251, 10255, 10426, 10521, 10525, 10575, 11259, 11439, 11844, 11848, 12006, 12060, 12384, 12505, 12546, 12550, 12595, 12600, 12762, 12768, 12798, 12843, 12955, 12964 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Nontrivial means that there must be at least two factors.

REFERENCES

Clifford A. Pickover, A Passion for Mathematics, Wiley, 2005; see p. 65.

LINKS

Table of n, a(n) for n=1..39.

Gordon Hamilton, Three integer sequences from recreational mathematics, Video (2013?).

EXAMPLE

E.g. 1395 = 31*9*5.

CROSSREFS

The following sequences are all closely related: A020342, A014575, A080718, A048936, A144563.

Sequence in context: A025388 A025389 A025380 * A179482 A009944 A203566

Adjacent sequences:  A020339 A020340 A020341 * A020343 A020344 A020345

KEYWORD

nonn,base

AUTHOR

David W. Wilson

EXTENSIONS

Edited by N. J. A. Sloane, Jan 03 2009

STATUS

approved

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

Content is available under The OEIS End-User License Agreement .

Last modified September 16 23:31 EDT 2014. Contains 246831 sequences.