|
|
A064830
|
|
a(n) = gcd(n, prime(n)^2 - 1).
|
|
4
|
|
|
1, 2, 3, 4, 5, 6, 1, 8, 3, 10, 1, 12, 1, 14, 3, 8, 1, 6, 1, 20, 3, 2, 1, 24, 1, 2, 3, 4, 1, 6, 1, 8, 3, 2, 5, 12, 1, 2, 3, 8, 1, 42, 1, 4, 9, 2, 1, 48, 1, 10, 3, 4, 1, 18, 1, 8, 3, 2, 1, 60, 1, 2, 63, 16, 13, 6, 1, 4, 3, 70, 1, 72, 1, 2, 15, 4, 1, 6, 1, 80, 3, 2, 1, 84, 5, 2, 3, 8, 1, 6, 13, 4, 3, 2
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
EXAMPLE
|
A000040(20) = 71, gcd(20, (71-1)*(71+1)) = 10 * gcd(2, 7*72) = 20 = a(20).
|
|
MATHEMATICA
|
Table[ GCD[n, Prime[n]^2 - 1], {n, 1, 100} ]
|
|
PROG
|
(PARI) { for (n=1, 1000, write("b064830.txt", n, " ", gcd(n, prime(n)^2 - 1)) ) } \\ Harry J. Smith, Sep 27 2009
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|