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Search: id:A055245
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| A055245 |
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Numerator sequence of mean length of certain stackings of n+1 squares on a double staircase. |
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+0
2
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| 1, 1, 5, 12, 28, 61, 127, 257, 507, 982, 1872, 3523, 6557, 12089, 22105, 40128, 72380, 129809, 231611, 411337, 727455, 1281578, 2249856, 3936935, 6868537, 11950033, 20737613, 35901300, 62014396, 106897669, 183905143, 315806321, 541372131
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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Denominator sequence is A055244(n).
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REFERENCES
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L. Turban, Lattice animals on a staircase and Fibonacci numbers, J.Phys. A 33 (2000) 2587-2595.
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FORMULA
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G.f.: (1-2*x+2*x^2+2*x^3-3*x^4-x^5)/(1-x-x^2)^3 (from Turban reference eq.(3.11)).
a(n)= ((5*n^2+3*n-27)*F(n)+(19*n+25)*F(n+1))/25 with F(n)=A000045(n) (Fibonacci numbers) (from Turban reference eq.(3.12)).
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CROSSREFS
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A000045, A055244.
Adjacent sequences: A055242 A055243 A055244 this_sequence A055246 A055247 A055248
Sequence in context: A128439 A038376 A002767 this_sequence A000465 A069306 A009412
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KEYWORD
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nonn,easy
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AUTHOR
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Wolfdieter Lang (wolfdieter.lang(AT)physik.uni-karlsruhe.de), May 10 2000
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