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Search: id:A006235
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| A006235 |
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Complexity of doubled cycle (regarding case n = 2 as a multigraph).
(Formerly M4849)
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+0
3
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| 1, 12, 75, 384, 1805, 8100, 35287, 150528, 632025, 2620860, 10759331, 43804800, 177105253, 711809364, 2846259375, 11330543616, 44929049777, 177540878700, 699402223099, 2747583822720, 10766828545725, 42095796462852, 164244726238343
(list; graph; listen)
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OFFSET
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1,2
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REFERENCES
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S. Plouffe, Approximations de S\'{e}ries G\'{e}n\'{e}ratrices et Quelques Conjectures}, Dissertation, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.
G. Kreweras, Complexite et circuits Euleriens dans la sommes tensorielles de graphes, J. Combin. Theory, B 24 (1978), 202-212.
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LINKS
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S. Plouffe, Approximations de S\'{e}ries G\'{e}n\'{e}ratrices et Quelques Conjectures}, Dissertation, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.
S. Plouffe, 1031 Generating Functions and Conjectures, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.
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FORMULA
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G.f.: x(1+2x-10x^2+2x^3+x^4)/((1-x)*(1-4x+x^2))^2.
a(n)=10a(n-1)-35a(n-2)+52a(n-3)-35a(n-4)+10a(n-5)-a(n-6), n>5.
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MAPLE
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A006235:=(1+2*z-10*z**2+2*z**3+z**4)/(z-1)**2/(z**2-4*z+1)**2; [Conjectured by S. Plouffe in his 1992 dissertation.]
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PROGRAM
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(PARI) a(n)=if(n<0, 0, polcoeff(x*(1+2*x-10*x^2+2*x^3+x^4)/((1-x)*(1-4*x+x^2))^2+x*O(x^n), n))
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CROSSREFS
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Cf. A006237. Apart from a(2) coincides with A072373.
Sequence in context: A003368 A092867 A053310 this_sequence A009642 A051104 A044199
Adjacent sequences: A006232 A006233 A006234 this_sequence A006236 A006237 A006238
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KEYWORD
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nonn
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AUTHOR
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njas
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EXTENSIONS
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More terms from Michael Somos, Jul 19 2002
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