id:A066247 - OEIS Search Results

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Characteristic function of composite numbers: 1 if n is composite else 0.

+0
8

0, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 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, 1, 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; listen)

	OFFSET	`1,1`
	COMMENT	`a(n) = signum(A066246(n)), where signum = A057427. For n > 1: a(n) = 1 - A010051(n) = A005171(n).`
	LINKS	`Index entries for characteristic functions`
	FORMULA	`a(n)={[(n+1)-(n-1)!^2] mod n}, with n>=1 - Paolo P. Lava (ppl(AT)spl.at), Jan 29 2008`
	MAPLE	`P:=proc(n) local i; for i from 1 by 1 to n do print(((i+1)-(i-1)!^2) mod i); od; end: P(100); - Paolo P. Lava (ppl(AT)spl.at), Jan 29 2008`
	CROSSREFS	`Cf. A002808, A010051, A005171.` `Sequence in context: A064911 A099618 A106002 this_sequence A151774 A095792 A093385` `Adjacent sequences: A066244 A066245 A066246 this_sequence A066248 A066249 A066250`
	KEYWORD	`nonn`
	AUTHOR	`Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Dec 09 2001`

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Last modified November 24 23:16 EST 2009. Contains 167481 sequences.

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