|
|
A069564
|
|
a(1) = 2; a(n) = k*a(n-1) + 1 is a multiple of n-th prime with k > 1.
|
|
1
|
|
|
2, 9, 55, 441, 4411, 13234, 26469, 238222, 476445, 3335116, 60032089, 1680898493, 15128086438, 605123457521, 6051234575211, 90768518628166
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
a(16) is divisible by the 17th prime, so there can be no a(17). - Robert Israel, Feb 23 2017
|
|
LINKS
|
|
|
EXAMPLE
|
After a(2) = 9 we have a(3) = 6*9 + 1 = 55 since this is smallest such number divisible by the third prime 5.
|
|
MAPLE
|
a[1]:= 2:
for n from 2 to 16 do
v:= chrem([1, 0], [a[n-1], ithprime(n)]);
if v = a[n-1]+1 then a[n]:= v + a[n-1]*ithprime(n) else a[n]:= v fi
od:
|
|
MATHEMATICA
|
a = 1; Do[k = 2; While[ !IntegerQ[(k*a + 1)/Prime[n]], k++ ]; a = (k*a + 1); Print[a], {n, 1, 16}]
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,fini,full
|
|
AUTHOR
|
|
|
EXTENSIONS
|
Corrected and extended by Larry Reeves (larryr(AT)acm.org), Jul 02 2002
|
|
STATUS
|
approved
|
|
|
|