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A175093
a(1) = 1, a(2) = 2, for n >= 3, a(n) = smallest prime > a(n-1) such that a(n) mod a(n-1) = a(n-2).
4
1, 2, 3, 5, 13, 31, 137, 853, 6961, 28697, 179143, 6836131, 68540453, 966402473, 15530980021, 94152282599, 203835545219, 2540178825227, 61168127350667, 6119352913891927, 220357873027460039, 16312601956945934813, 750600047892540461437, 33042714709228726238041
OFFSET
1,2
COMMENTS
Essentially the same as A072999. [R. J. Mathar, Feb 01 2010]
a(397) has 1003 digits. - Michael S. Branicky, Dec 21 2023
LINKS
Michael S. Branicky, Table of n, a(n) for n = 1..396
PROG
(Python)
from gmpy2 import is_prime
from itertools import count, islice
def agen(): # generator of terms
c, b = 1, 2
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(), 24))) # Michael S. Branicky, Dec 21 2023
CROSSREFS
Sequence in context: A355512 A060434 A072999 * A342180 A345076 A353582
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Jan 31 2010
EXTENSIONS
Name corrected and a(16) and beyond from Michael S. Branicky, Dec 21 2023
STATUS
approved