

A131378


Starting with 0, the sequence a(n) changes from 0 to 1 or back when the next number n is a prime.


3



0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 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, 1, 1, 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, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1
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OFFSET

0,1


COMMENTS

Zero together with A071986  Omar E. Pol, Feb 19 2011.


LINKS

Table of n, a(n) for n=0..100.


EXAMPLE

n = 0, 1, 2, 3, 4, 5, etc..
a(n)= 0, 0, 1, 0, 0, 1, etc.
Starting with 0 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:=0; 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. A131377.
Cf. A071986  Omar E. Pol, Feb 19 2011.
Sequence in context: A116178 A028999 A091244 * A014707 A106138 A064990
Adjacent sequences: A131375 A131376 A131377 * A131379 A131380 A131381


KEYWORD

easy,nonn


AUTHOR

Paolo P. Lava and Giorgio Balzarotti, Jul 04 2007


STATUS

approved



