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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
Sequence in context: A135658 A228589 A066862 * A103540 A065159 A240265
KEYWORD
nonn
AUTHOR
Paolo P. Lava, Aug 27 2013
STATUS
approved

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Last modified March 18 22:50 EDT 2024. Contains 370951 sequences. (Running on oeis4.)