id:A076217 - OEIS Search Results

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a(1)=1, a(n) = a(n-1) + n * (sign(n-a(n-1)).

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1, 3, 3, 7, 2, 8, 1, 9, 9, 19, 8, 20, 7, 21, 6, 22, 5, 23, 4, 24, 3, 25, 2, 26, 1, 27, 27, 55, 26, 56, 25, 57, 24, 58, 23, 59, 22, 60, 21, 61, 20, 62, 19, 63, 18, 64, 17, 65, 16, 66, 15, 67, 14, 68, 13, 69, 12, 70, 11, 71, 10, 72, 9, 73, 8, 74, 7, 75, 6, 76, 5, 77, 4, 78, 3, 79, 2, 80 (list; graph; listen)

	OFFSET	`1,2`
	FORMULA	`If 3^n>2m>= 23^(n-1); a(3^n-2m) = m; if 3^n>2m+1>=23^(n-1)+1 a(3^n-2m-1) = 3^n - m; special case of partial sum : sum(k=1, 3^n, a(k)) = (3/8)*(9^n-1) + (3^(n+1)-1)/2`
	EXAMPLE	`a(2) = a(1)+sign(2-a(1))*2 = 1 + 2 = 3`
	CROSSREFS	`Cf. A005132.` `Sequence in context: A118031 A059527 A101457 this_sequence A089488 A076560 A096915` `Adjacent sequences: A076214 A076215 A076216 this_sequence A076218 A076219 A076220`
	KEYWORD	`nice,nonn`
	AUTHOR	`Benoit Cloitre (benoit7848c(AT)orange.fr), Nov 03 2002`

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Last modified December 18 21:37 EST 2009. Contains 171024 sequences.

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