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A376201
Fixed points in A376198.
10
1, 2, 3, 4, 11, 12, 27, 28, 59, 60, 123, 124, 125, 126, 255, 256, 515, 516, 517, 518, 519, 520, 1043, 1044, 1045, 1046, 1047, 1048, 2099, 2100, 2101, 2102, 2103, 2104, 2105, 2106, 2107, 2108, 2109, 2110, 4223, 4224, 4225, 4226, 4227, 4228, 8459, 8460, 16923, 16924, 16925, 16926, 33855, 33856, 67715, 67716, 67717, 67718, 67719
OFFSET
1,2
COMMENTS
Conjectures: the terms consist of runs of an even number (>1) of successive numbers that increase by 1 at each step; A376758(n) is one-half of the length of the n-th such run; and the run ends at A376751(n) - 1. - N. J. A. Sloane, Oct 07 2024
LINKS
Michael S. Branicky, Table of n, a(n) for n = 1..398
PROG
(Python)
from itertools import count, islice
from sympy import isprime, nextprime
def agen(): # generator of terms
an, smc, smp = 2, 4, 3
yield from [1, 2]
for n in count(3):
if not isprime(an):
an = smp if an == 2*smp else smc
else:
an = smp if smp < smc else smc
if an == smp: smp = nextprime(smp)
else:
smc += 1
while isprime(smc): smc += 1
if n == an: yield an
print(list(islice(agen(), 59))) # Michael S. Branicky, Oct 03 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Oct 03 2024
STATUS
approved