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

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A066478 Numbers having just twelve anti-divisors. 1
338, 450, 612, 722, 882, 1458, 1513, 1624, 1740, 1800, 2112, 2520, 2592, 2738, 3025, 3136, 3200, 3249, 3280, 3600, 3785, 3960, 4512, 5202, 5305, 5725, 6084, 6613, 7056, 7081, 7564, 8192, 8320, 8649, 9384, 9661, 10000, 10512, 10609, 12013, 12321 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

See A066272 for definition of anti-divisor.

LINKS

Table of n, a(n) for n=1..41.

Jon Perry, The Anti-Divisor

Jon Perry, The Anti-divisor [Cached copy]

Jon Perry, The Anti-divisor: Even More Anti-Divisors [Cached copy]

MAPLE

A066478:= proc(q)

local k, n, t;

for n from 1 to q do

t:=0; for k from 2 to n-1 do if abs((n mod k)-k/2)<1 then t:=t+1; fi; od;

if t=12 then print(n); fi; od; end:

A066478(10^10); # Paolo P. Lava, Feb 22 2013

MATHEMATICA

antid[n_] := Select[ Union[ Join[ Select[ Divisors[2n - 1], OddQ[ # ] && # != 1 & ], Select[ Divisors[2n + 1], OddQ[ # ] && # != 1 & ], 2n/Select[ Divisors[ 2*n], OddQ[ # ] && # != 1 &]]] }, # < n & ]]; Select[ Range[10^4], Length[ antid[ # ]] == 12 & ]

nd[n_]:=Count[Range[2, n-1], _?(Abs[Mod[n, #]-#/2]<1&)]; Select[Range[ 12500], nd[#]==12&] (* Harvey P. Dale, Jul 11 2012 *)

CROSSREFS

Cf. A066272.

Sequence in context: A243483 A234625 A226539 * A261707 A202443 A188213

Adjacent sequences:  A066475 A066476 A066477 * A066479 A066480 A066481

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Jan 02 2002

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 December 12 01:57 EST 2019. Contains 329948 sequences. (Running on oeis4.)