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

 

Logo

The submissions stack has been unacceptably high for several months now. Please voluntarily restrict your submissions and please help with the editing. (We don't want to have to impose further limits.)

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A105935 Indices of Lucas 7-step numbers A104621 which have a nontrivial divisor in common with index. 0
6, 12, 18, 20, 36, 42, 54, 57, 60, 65, 87, 93, 99, 100, 104, 105, 108 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Wanted: closed-form formula for this as exists for Fibonacci and Lucas numbers. Lucas 7-step numbers also known as heptanacci-Lucas numbers. The prime Lucas 7-step numbers are A105768, their indices being A104622.

LINKS

Table of n, a(n) for n=0..16.

FORMULA

gcd(a(n), A104621(a(n))) > 1.

EXAMPLE

gcd(a(n), A104621(6,12,18,36,57,60,87,93,108)) = 3,

gcd(a(n), A104621(20,65,100,105)) = 5,

gcd(a(n), A104621(42)) = 7,

gcd(a(n), A104621(54,99)) = 9,

gcd(a(n), A104621(104)) = 13.

CROSSREFS

Cf. A104621, A105285, A105289.

Sequence in context: A088723 A228870 A138939 * A221220 A046411 A160594

Adjacent sequences:  A105932 A105933 A105934 * A105936 A105937 A105938

KEYWORD

easy,nonn

AUTHOR

Jonathan Vos Post, Apr 26 2005

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 August 28 18:07 EDT 2015. Contains 261154 sequences.