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A290509 Number of irredundant sets in the n-Moebius ladder. 1
3, 5, 24, 81, 198, 542, 1550, 4497, 12732, 36210, 103579, 296250, 846303, 2417308, 6907329, 19737889, 56396602, 161138306, 460420182, 1315565326, 3758963099, 10740463167, 30688703123, 87686813826, 250547405698, 715888629071, 2045507376543, 5844625042904 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..200

Eric Weisstein's World of Mathematics, Irredundant Set

Eric Weisstein's World of Mathematics, Moebius Ladder

FORMULA

Empirical: a(n) = 3*a(n-1) - a(n-3) + 2*a(n-4) - 6*a(n-5) - 8*a(n-6) + 13*a(n-7) + 6*a(n-8) - 6*a(n-9) - 2*a(n-10) - 5*a(n-11) - 4*a(n-12) + 2*a(n-13) + 2*a(n-14) - a(n-15) + a(n-16) + 3*a(n-17) + 2*a(n-19) for n > 19. - Andrew Howroyd, Aug 05 2017

Empirical g.f.: x*(3 - 4*x + 9*x^2 + 12*x^3 - 46*x^4 - 20*x^5 + 11*x^6 + 28*x^7 - 18*x^8 - 8*x^9 + 21*x^10 - 4*x^11 + 18*x^12 + 8*x^13 - 15*x^14 + 4*x^15 + 23*x^16 + 14*x^18) / ((1 - x)*(1 - x^2 + x^4 + x^6)*(1 - 2*x - x^2 - 3*x^3 - 5*x^4 + 2*x^5 + 6*x^6 + 5*x^7 + 4*x^8 + 4*x^9 + 3*x^10 + 2*x^11 + 2*x^12)). - Colin Barker, Aug 05 2017

CROSSREFS

Cf. A284663, A290337.

Sequence in context: A336425 A230985 A286427 * A347947 A208800 A356274

Adjacent sequences:  A290506 A290507 A290508 * A290510 A290511 A290512

KEYWORD

nonn

AUTHOR

Eric W. Weisstein, Aug 04 2017

EXTENSIONS

a(1)-a(2) and terms a(10) and beyond from Andrew Howroyd, Aug 05 2017

STATUS

approved

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Last modified October 3 14:19 EDT 2022. Contains 357237 sequences. (Running on oeis4.)