id:A069735 - OEIS Search Results

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Number of regular orientable coverings of the Klein bottle with 2n lists.

+0
2

1, 3, 2, 5, 2, 6, 2, 7, 3, 6, 2, 10, 2, 6, 4, 9, 2, 9, 2, 10, 4, 6, 2, 14, 3, 6, 4, 10, 2, 12, 2, 11, 4, 6, 4, 15, 2, 6, 4, 14, 2, 12, 2, 10, 6, 6, 2, 18, 3, 9, 4, 10, 2, 12, 4, 14, 4, 6, 2, 20, 2, 6, 6, 13, 4, 12, 2, 10, 4, 12, 2, 21, 2, 6, 6, 10, 4, 12, 2, 18, 5, 6, 2, 20, 4, 6, 4, 14, 2, 18 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`Multiplicative defined by f(2^k)=2k+1 and f(p^k)=k+1 for k>0 and an odd prime p.` `Equals row sums of triangle A143110 - Gary W. Adamson (qntmpkt(AT)yahoo.com), Jul 25 2008`
	LINKS	`V. A. Liskovets and A. Mednykh, Number of non-orientable coverings of the Klein bottle`
	FORMULA	`a(n)=d(n)+d(n/2) for even n and =d(n) otherwise where d(n) is the number of divisors of n (A000005).` `G.f.: Sum_{k>0} x^k(1+2x^k)/(1-x^(2*k)). - Vladeta Jovovic (vladeta(AT)Eunet.yu), Dec 16 2002`
	CROSSREFS	`Cf. A000005.` `Sequence in context: A057034 A075410 A023513 this_sequence A046524 A105222 A086571` `Cf. A143110.` `Adjacent sequences: A069732 A069733 A069734 this_sequence A069736 A069737 A069738`
	KEYWORD	`mult,easy,nonn`
	AUTHOR	`Valery A. Liskovets (liskov(AT)im.bas-net.by), Apr 07 2002`
	EXTENSIONS	`Corrected by T. D. Noe (noe(AT)sspectra.com), Nov 13 2006`

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Last modified September 8 13:07 EDT 2008. Contains 143486 sequences.

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