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A347313 Index of prime(n) in A347113, or -1 if that prime never appears. 6
8, 11, 7, 20, 28, 19, 37, 51, 53, 47, 101, 116, 58, 63, 99, 81, 136, 146, 159, 153, 115, 213, 176, 197, 302, 151, 215, 223, 169, 230, 276, 274, 255, 188, 233, 318, 440, 341, 347, 359, 369, 282, 386, 396, 405, 520, 638, 460, 472, 698, 357, 492, 507, 514, 529, 535, 558, 702 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Conjecture: every prime appears in A347113 (every number, in fact).
The graph shows three three strong lines (and many other points). Can the primes on the three lines be described in a simple way?
LINKS
PROG
(Python)
from math import gcd
from sympy import prime
def A347313(n):
p = prime(n)
i, j, nset, m = 1, 2, {1}, 2
while True:
k = m
i += 1
while k == j or gcd(k, j) == 1 or k in nset:
k += 1
if k == p:
return i
j = k+1
nset.add(k)
while m in nset:
m += 1 # Chai Wah Wu, Sep 06 2021
CROSSREFS
Cf. A347113.
Sequence in context: A109596 A164801 A156925 * A077060 A123939 A134787
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Sep 06 2021
STATUS
approved

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Last modified March 3 17:50 EST 2024. Contains 370512 sequences. (Running on oeis4.)