id:A080278 - OEIS Search Results

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(3^(v_3(n)+1)-1)/2, where v_3(n) = highest power of 3 dividing n = A007949(n).

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1, 1, 4, 1, 1, 4, 1, 1, 13, 1, 1, 4, 1, 1, 4, 1, 1, 13, 1, 1, 4, 1, 1, 4, 1, 1, 40, 1, 1, 4, 1, 1, 4, 1, 1, 13, 1, 1, 4, 1, 1, 4, 1, 1, 13, 1, 1, 4, 1, 1, 4, 1, 1, 40, 1, 1, 4, 1, 1, 4, 1, 1, 13, 1, 1, 4, 1, 1, 4, 1, 1, 13, 1, 1, 4, 1, 1, 4, 1, 1, 121, 1, 1, 4, 1, 1, 4, 1, 1, 13, 1, 1, 4, 1, 1, 4, 1, 1 (list; graph; listen)

	OFFSET	`1,3`
	COMMENT	`Denominator of quotient=sigma[3n]/sigma[n]. - Labos E. (labos(AT)ana.sote.hu), Nov 04 2003`
	LINKS	`Klaus Brockhaus, Illustration of A080278 and A080333`
	FORMULA	`G.f. sum(k>=0, 3^k*x^3^k/(1-x^3^k)). - Ralf Stephan (ralf(AT)ark.in-berlin.de), Jun 15 2003`
	MAPLE	`A080278 := n->(3^(A007949(n)+1)-1)/2;`
	MATHEMATICA	`Table[Denominator[DivisorSigma[1, 3*n]/DivisorSigma[1, n]], {n, 1, 128}]`
	CROSSREFS	`Cf. A007949, A080333.` `Sequence in context: A146325 A069289 A097322 this_sequence A070085 A131776 A010322` `Adjacent sequences: A080275 A080276 A080277 this_sequence A080279 A080280 A080281`
	KEYWORD	`nonn,mult`
	AUTHOR	`N. J. A. Sloane (njas(AT)research.att.com), Mar 19 2003`

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Last modified November 27 22:38 EST 2009. Contains 167602 sequences.

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