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A131377
Starting with 1, the sequence a(n) changes from 1 to 0 or back when the next number n is a prime.
2
1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0
OFFSET
0,1
FORMULA
a(n) = 1 - A071986(n).
EXAMPLE
n = 0, 1, 2, 3, 4, 5, etc..
a(n)= 1, 1, 0, 1, 1, 0, etc.
Starting with 1 the sequence changes when we move from 1 to 2 because 2 is prime, again from 2 to 3 because also 3 is prime, then from 4 to 5 being 5 prime and so on.
MAPLE
P:=proc(n) local i, k; k:=1; for i from 0 by 1 to n do if isprime(i) then if k=1 then k:=0; else k:=1; fi; fi; print(k); od; end: P(100);
CROSSREFS
Cf. A131378.
Cf. A071986. - Omar E. Pol, Feb 19 2011
Sequence in context: A014577 A157926 A263243 * A364639 A342991 A285898
KEYWORD
easy,nonn
AUTHOR
STATUS
approved