|
|
A228590
|
|
Starting from a(1)=1, a(n) is the minimum integer greater than a(n-1) such that a(n)+a(n-1), a(n)*a(n-1)+1 and a(n)*a(n-1)-1 are all primes.
|
|
3
|
|
|
1, 4, 15, 16, 27, 74, 375, 398, 465, 482, 945, 962, 1149, 1228, 1485, 1624, 1737, 1820, 1941, 1990, 2031, 2690, 2787, 3040, 3327, 3436, 3525, 3704, 3855, 3934, 4383, 4484, 4515, 4712, 6375, 6592, 7239, 7322, 7545, 7616, 7935, 8138, 9381, 9518, 11445, 11594
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
Terms are alternately odd and even.
|
|
LINKS
|
|
|
EXAMPLE
|
a(4)=16 and 27 is the minimum integer greater than 16 such that 16+27=43, 16*27-1=431, 16*27+1=433 are all primes.
|
|
MAPLE
|
with(numtheory); P:=proc(q) local a, b, n; a:=1; b:=0; print(a);
for n from 1 to q do while not isprime(a+b) and not isprime (a*b+1) and not isprime (a*b-1) do
b:=b+2; od; print(b); a:=b; b:=b+1; od; print(); end: P(10^4);
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|