A083055 - OEIS

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A083055

a(n) = cardinality{ k<=n / A083054(k)=1}.

1, 1, 1, 1, 1, 2, 2, 3, 3, 3, 4, 4, 5, 5, 6, 6, 6, 7, 7, 8, 8, 8, 8, 8, 9, 9, 10, 10, 10, 10, 10, 11, 11, 12, 12, 12, 13, 13, 14, 14, 14, 14, 14, 15, 15, 16, 16, 16, 16, 16, 17, 17, 18, 18, 18, 18, 18, 19, 19, 20, 20, 20, 21, 21, 22, 22, 22, 22, 22, 23, 23, 24, 24, 24, 24, 24, 25, 25 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,6`
	LINKS	`Boris Gourevitch, Graph of A083057`
	FORMULA	`a(n) = n/3 + O(n) (it seems O(n) could be replaced with O(log(n)))`
	PROG	`(PARI) {a(n)=if(n<1, 0, sum(k=1, n, sqrtint(3k^2)-3sqrtint(k^2\3)==1))} /* Michael Somos Aug 31 2006 */`
	CROSSREFS	`Cf. A083038, A083054, A083056, A083057.` `Sequence in context: A194986 A054071 A028827 * A195072 A121828 A057357` `Adjacent sequences: A083052 A083053 A083054 * A083056 A083057 A083058`
	KEYWORD	`nonn`
	AUTHOR	`Benoit Cloitre (benoit7848c(AT)orange.fr), Apr 18 2003`

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Last modified February 15 14:02 EST 2012. Contains 205811 sequences.