id:A133829 - OEIS Search Results

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a(n) = the largest "non-isolated divisor" of 2n. A positive divisor k of n is non-isolated if k-1 or k+1 also divides n.

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2, 2, 3, 2, 2, 4, 2, 2, 3, 5, 2, 4, 2, 2, 6, 2, 2, 4, 2, 5, 7, 2, 2, 4, 2, 2, 3, 8, 2, 6, 2, 2, 3, 2, 2, 9, 2, 2, 3, 5, 2, 7, 2, 2, 10, 2, 2, 4, 2, 5, 3, 2, 2, 4, 11, 8, 3, 2, 2, 6, 2, 2, 7, 2, 2, 12, 2, 2, 3, 5, 2, 9, 2, 2, 6, 2, 2, 13, 2, 5, 3, 2, 2, 8, 2, 2, 3, 2, 2, 10, 14, 2, 3, 2, 2, 4, 2, 2, 3 (list; graph; listen)

	OFFSET	`1,1`
	COMMENT	`No odd integer has any non-isolated divisors.`
	MAPLE	`A133829 := proc(n) local divs, k, i ; divs := sort(convert(numtheory[divisors](2*n), list)) ; for i from 1 to nops(divs) do k := op(-i, divs) ; if k-1 in divs or k+1 in divs then RETURN(k) ; fi ; od: RETURN(0) ; end: seq(A133829(n), n=1..100) ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 19 2007`
	CROSSREFS	`Cf. A133780, A133828.` `Adjacent sequences: A133826 A133827 A133828 this_sequence A133830 A133831 A133832` `Sequence in context: A138143 A106441 A131836 this_sequence A086454 A069360 A068050`
	KEYWORD	`nonn`
	AUTHOR	`Leroy Quet (qq-quet(AT)mindspring.com), Sep 25 2007`
	EXTENSIONS	`More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 19 2007`

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Last modified October 6 16:13 EDT 2008. Contains 144667 sequences.

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