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A175208
a(1) = 1, a(2) = 7, for n >= 3, a(n) = smallest prime > a(n-1) such that a(n) mod a(n-1) = a(n-2).
3
1, 7, 29, 181, 4373, 61403, 2583299, 41394187, 85371673, 895110917, 16197368179, 98079319991, 800831928107, 3301407032419, 159268369484219, 5736962708464303, 46054970037198643, 4703343906502725889, 18859430596048102199, 155578788674887543481, 4375065513492899319667
OFFSET
1,2
COMMENTS
It appears that the definition should include the condition that the sequence is strictly increasing - true? - N. J. A. Sloane, Jan 27 2019
a(390) has 1002 digits. - Michael S. Branicky, Dec 21 2023
LINKS
Michael S. Branicky, Table of n, a(n) for n = 1..389 (terms 1..33 from Charlie Neder)
PROG
(Python)
from gmpy2 import is_prime
from itertools import count, islice
def agen(): # generator of terms
c, b = 1, 7
yield from [c, b]
for n in count(3):
a = next(c + b*i for i in count(1) if is_prime(c+b*i))
c, b = b, a
yield a
print(list(islice(agen(), 21))) # Michael S. Branicky, Dec 21 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Mar 04 2010
EXTENSIONS
a(12)-a(20) from Charlie Neder, Jan 25 2019
Name corrected per N. J. A. Sloane's comment by Michael S. Branicky, Dec 21 2023
STATUS
approved