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A354921
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Positions of odd terms in A182665.
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5
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2, 3, 4, 5, 7, 8, 9, 11, 12, 13, 16, 17, 19, 21, 23, 25, 27, 28, 29, 30, 31, 32, 35, 37, 39, 40, 41, 43, 44, 47, 48, 49, 53, 55, 56, 57, 59, 60, 61, 64, 66, 67, 71, 73, 75, 76, 79, 80, 81, 83, 85, 89, 90, 92, 93, 97, 99, 101, 102, 103, 104, 105, 107, 108, 109, 111, 113, 117, 119, 120, 121, 124, 125, 126, 127, 128
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OFFSET
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1,1
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COMMENTS
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Numbers k such that the parity of A344005(k) differs from the parity of k itself.
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LINKS
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PROG
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(PARI)
A354920(n) = forstep(x=n-1, 0, -1, if(!((x*(x-1))%n), return(x%2)));
(Python 3.8+)
from itertools import combinations, islice, count
from math import prod
from sympy import factorint
from sympy.ntheory.modular import crt
def A354921_gen(startvalue=2): # generator of terms >= startvalue
for n in count(max(startvalue, 2)):
plist = tuple(p**q for p, q in factorint(n).items())
if len(plist) == 1 or (n-int(min(min(crt((m, n//m), (0, -1))[0], crt((n//m, m), (0, -1))[0]) for m in (prod(d) for l in range(1, len(plist)//2+1) for d in combinations(plist, l))))) & 1:
yield n
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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