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A202238 Characteristic function of positive integers not prime and not a power of 2. 1
0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 1, 0, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
A111775(n) = 0 if and only if a(n) = 0.
A111787(n) = 0 if and only if a(n) = 0.
a(n) = 1 for n in A111774. - Michel Marcus, Aug 28 2017
PROG
(PARI) {a(n) = n>0 && !isprime(n) && n != 2^valuation(n, 2)}
CROSSREFS
Sequence in context: A169672 A011672 A353492 * A144194 A144196 A156659
KEYWORD
nonn,easy
AUTHOR
Michael Somos, Dec 16 2011
STATUS
approved

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Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)