

A105935


Indices of Lucas 7step 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
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OFFSET

0,1


COMMENTS

Wanted: closedform formula for this as exists for Fibonacci and Lucas numbers. Lucas 7step numbers also known as heptanacciLucas numbers. The prime Lucas 7step 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



