id:A066376 - OEIS Search Results

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Number of "divisors" d < n such that there is another d' < n with d*d' = n.

+0
2

0, 1, 1, 2, 1, 3, 2, 3, 1, 3, 1, 5, 1, 5, 4, 4, 1, 3, 1, 5, 2, 3, 1, 7, 1, 3, 3, 8, 1, 9, 7, 5, 1, 3, 1, 5, 1, 3, 1, 7, 1, 5, 1, 5, 3, 3, 3, 9, 1, 3, 3, 5, 1, 7, 3, 11, 1, 3, 3, 14, 3, 15, 13, 6, 1, 3, 1, 5, 1, 3, 1, 7, 2, 3, 1, 5, 1, 3, 1, 9, 1, 3, 1, 8, 4, 3, 1, 7, 1, 7, 3, 5, 1, 7, 5, 11, 1 (list; graph; listen)

	OFFSET	`1,4`
	COMMENT	`Define "+" as binary bitwise inclusive-OR and then implement "" as shift-and-"+". Note that is commutative and associative and distributes over +.`
	EXAMPLE	`14 has 5 "divisors": 1, 2, 3, 6, 7, since for example 27 = 10111 = 1110 OR 0000 = 1110; 36 = 11110 = 1100 OR 0110 = 1110.`
	CROSSREFS	`Cf. A067139 ("primes").` `Sequence in context: A101608 A102853 A107337 this_sequence A151682 A159918 A108663` `Adjacent sequences: A066373 A066374 A066375 this_sequence A066377 A066378 A066379`
	KEYWORD	`nonn,easy,nice`
	AUTHOR	`Marc LeBrun (mlb(AT)well.com), Dec 22 2001`

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.

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