id:A055718 - OEIS Search Results

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Number of distinct prime factors of EulerPhi(n!) minus number of primes dividing n!.

+0
2

0, 1, 1, 1, 2, 1, 2, 2, 2, 1, 2, 2, 3, 2, 2, 2, 3, 3, 4, 4, 4, 3, 4, 4, 4, 3, 3, 3, 4, 4, 5, 5, 5, 4, 4, 4, 5, 4, 4, 4, 5, 5, 6, 6, 6, 5, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 6, 7, 7, 8, 7, 7, 7, 7, 7, 8, 8, 8, 8, 9, 9, 10, 9, 9, 9, 9, 9, 10, 10, 10, 9, 10, 10, 10, 9, 9, 9, 10, 10, 10, 10, 10, 9, 9, 9, 10, 10 (list; graph; listen)

	OFFSET	`1,5`
	COMMENT	`Number of primes dividing Phi(n!) is smaller than`
	FORMULA	`A001221(n!)-A001221(A000010(A000142(n)))= A000720(n)-A001221(A048855(n)))` `a(n)=PrimePi[n]-PrimePi[Floor[n/2]].`
	EXAMPLE	`Prime factors of 100! are the 25 primes below 100,`
	CROSSREFS	`Cf. A000142, A000010, A000720, A001221, A055679.` `Sequence in context: A002321 A043530 A164995 this_sequence A007302 A099910 A043555` `Adjacent sequences: A055715 A055716 A055717 this_sequence A055719 A055720 A055721`
	KEYWORD	`nonn`
	AUTHOR	`Labos E. (labos(AT)ana.sote.hu), Jul 11 2000`

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

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