A137671 - OEIS

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A137671

a(n+1) = number of preceding terms having in binary representation the same number of ones as a(n).

1, 1, 2, 3, 1, 4, 5, 2, 6, 3, 4, 7, 1, 8, 9, 5, 6, 7, 2, 10, 8, 11, 3, 9, 10, 11, 4, 12, 12, 13, 5, 14, 6, 15, 1, 13, 7, 8, 14, 9, 16, 15, 2, 16, 17, 17, 18, 19, 10, 20, 21, 11, 12, 22, 13, 14, 15, 3, 23, 4, 18, 24, 25, 16, 19, 17, 26, 18, 27, 5, 28, 19, 20, 29, 6, 30, 7, 21, 22, 23, 8 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,3`
	COMMENTS	`A137672(n) = A000120(a(a(n));` `a(A137673(n)) = n and a(m) < n for m < A137673(n).` `a(n) = 1 iff a(n-1) = 2^k - 1: a(A137674(n)) = 1.`
	LINKS	`R. Zumkeller, Table of n, a(n) for n = 1..10000` `Index entries for sequences related to binary expansion of n`
	EXAMPLE	`n=4: a(3) = 2 = '10', A000120(2) = 1, therefore: a(4) = #{a(1)=1='1', a(2)=1, a(3)=2='10'} = 3;` `n=5: a(4) = 3 = '11', A000120(3) = 2, therefore: a(5) = #{a(4)} = 1;` `n=6: a(5) = 1 = '1', A000120(1) = 1, therefore: a(6) = #{a(1)=1='1', a(2)=1, a(3)=2='10', a(5)} = 4.`
	CROSSREFS	`Cf. A000120.` `Sequence in context: A092942 A131225 A221919 * A026370 A078446 A055447` `Adjacent sequences: A137668 A137669 A137670 * A137672 A137673 A137674`
	KEYWORD	`nonn`
	AUTHOR	`Reinhard Zumkeller, Feb 05 2008`
	STATUS	`approved`

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Last modified May 24 22:42 EDT 2013. Contains 225631 sequences.