A290509 Number of irredundant sets in the n-Moebius ladder.
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
Offset: 1
Keywords
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
Extensions
a(1)-a(2) and terms a(10) and beyond from Andrew Howroyd, Aug 05 2017