A106549 - OEIS

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A106549

a(n) = -1 iff 2*n+1 is prime, a(n)= 1 iff 2*n+1 is prime square, else a(n) = 0.

0, -1, -1, -1, 1, -1, -1, 0, -1, -1, 0, -1, 1, 0, -1, -1, 0, 0, -1, 0, -1, -1, 0, -1, 1, 0, -1, 0, 0, -1, -1, 0, 0, -1, 0, -1, -1, 0, 0, -1, 0, -1, 0, 0, -1, 0, 0, 0, -1, 0, -1, -1, 0, -1, -1, 0, -1, 0, 0, 0, 1, 0, 0, -1, 0, -1, 0, 0, -1, -1, 0, 0, 0, 0, -1, -1, 0, 0, -1, 0, 0, -1, 0, -1, 1, 0, -1 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,1`
	EXAMPLE	`a(1)=0 because 1 is not prime and neither prime square;` `a(2)=-1 because 3 is a prime;` `a(5)=1 because 9 is a prime square 3^2.`
	CROSSREFS	`Sequence in context: A122895 A097325 A167393 * A075897 A135947 A101040` `Adjacent sequences: A106546 A106547 A106548 * A106550 A106551 A106552`
	KEYWORD	`easy,sign`
	AUTHOR	`Giovanni Teofilatto (g.teofilatto(AT)tiscalinet.it), May 09 2005`

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Last modified February 18 00:14 EST 2012. Contains 206085 sequences.