id:A147645 - OEIS Search Results

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Number of distinct Mersenne primes dividing n.

+0
2

0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 2, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 2, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 1, 2, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 2, 0, 0, 1, 0, 0, 1, 1, 0, 2, 0, 0, 1, 0, 1, 1, 0 (list; graph; listen)

	OFFSET	`1,21`
	EXAMPLE	`a(21)=2 because 1, 3, 7 and 21 are divisors of 21. Then 21 has two divisors that are Mersenne primes (A000668): 3 and 7.`
	CROSSREFS	`Cf. A000668, A001221, A080225.` `Sequence in context: A078595 A078128 A112607 this_sequence A091970 A093955 A081603` `Adjacent sequences: A147642 A147643 A147644 this_sequence A147646 A147647 A147648`
	KEYWORD	`easy,nonn`
	AUTHOR	`Omar E. Pol (info(AT)polprimos.com), Nov 09 2008`

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

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