id:A075159 - OEIS Search Results

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Run lengths in the binary expansion of n-1 gives the vector of exponents in prime factorization of a(n), with the least significant run corresponding to the exponent of the least prime, 2.

+0
3

1, 2, 3, 4, 6, 5, 9, 8, 12, 15, 7, 10, 18, 25, 27, 16, 24, 45, 35, 30, 14, 11, 21, 20, 36, 75, 49, 50, 54, 125, 81, 32, 48, 135, 175, 90, 70, 77, 105, 60, 28, 33, 13, 22, 42, 55, 63, 40, 72, 225, 245, 150, 98, 121, 147, 100, 108, 375, 343, 250, 162, 625, 243, 64, 96, 405 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`To make this a permutation of nonnegative integers, we subtract one from each run count except for the most significant run, e.g. a(12) = 10, as 12-1 = 11 = 1011 and 10 = 5^1 * 3^(1-1) * 2^(2-1).`
	LINKS	`Index entries for sequences that are permutations of the natural numbers`
	CROSSREFS	`Inverse of A075160. a(n) = A075157(n-1)+1.` `Sequence in context: A054582 A099884 A118315 this_sequence A095424 A064275 A080998` `Adjacent sequences: A075156 A075157 A075158 this_sequence A075160 A075161 A075162`
	KEYWORD	`nonn`
	AUTHOR	`Antti Karttunen Sep 13 2002`

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Last modified November 23 17:09 EST 2009. Contains 167438 sequences.

AT&T Labs Research