A137688 - OEIS

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A137688

2^A003056: 2^n appears n+1 times.

1, 2, 2, 4, 4, 4, 8, 8, 8, 8, 16, 16, 16, 16, 16, 32, 32, 32, 32, 32, 32, 64, 64, 64, 64, 64, 64, 64, 128, 128, 128, 128, 128, 128, 128, 128, 256, 256, 256, 256, 256, 256, 256, 256, 256, 512, 512, 512, 512, 512, 512, 512, 512, 512, 512, 1024, 1024, 1024, 1024, 1024, 1024 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,2`
	COMMENTS	`First differences of A007664.`
	FORMULA	`a(n) = 2^[sqrt(2n+2)-.5] = 2^A003056(n) = A007664(n+1) - A007664(n)`
	PROG	`(PARI) A137688(n)= 1<<floor(sqrt(2*n+2)-.5)` `(Haskell)` `a137688 n = a137688_list !! n` `a137688_list = concat $ zipWith ($) (map replicate [1..]) (map (2^) [0..])` `-- Reinhard Zumkeller, Mar 18 2011`
	CROSSREFS	`Cf. A003056, A007664 (gives partial sums).` `Sequence in context: A033756 A124340 A071165 * A033720 A033728 A033744` `Adjacent sequences: A137685 A137686 A137687 * A137689 A137690 A137691`
	KEYWORD	`easy,nonn`
	AUTHOR	`M. F. Hasler (Maximilian.Hasler(AT)gmail.com), Feb 06 2008`

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Last modified February 17 19:13 EST 2012. Contains 206085 sequences.