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Revision History for A103943

(Underlined text is an addition; strikethrough text is a deletion.)

Showing entries 1-10 | older changes
A103943 Number of unrooted two-vertex n-edge maps in the plane (planar with a distinguished outside face).
(history; published version)
#19 by Bruno Berselli at Fri Aug 26 12:22:54 EDT 2016
STATUS

reviewed

approved

#18 by Michel Marcus at Fri Aug 26 11:38:15 EDT 2016
STATUS

proposed

reviewed

#17 by G. C. Greubel at Mon Aug 15 10:58:16 EDT 2016
STATUS

editing

proposed

#16 by G. C. Greubel at Mon Aug 15 10:58:03 EDT 2016
LINKS

G. C. Greubel, <a href="/A103943/b103943.txt">Table of n, a(n) for n = 1..1000</a>

STATUS

proposed

editing

#15 by Benedict W. J. Irwin at Sat Aug 13 14:09:32 EDT 2016
STATUS

editing

proposed

#14 by Benedict W. J. Irwin at Sat Aug 13 14:08:04 EDT 2016
FORMULA

G.f.: 1/8*(2/q^2 -2 + 1/p - 1/q + 2*sqrt(p^2-2*x)/sqrt(q^2+2*x) - sqrt(2 + 2*p*q)/(p*q)), where p=sqrt(1+4x4*x) and q=sqrt(1-4x4*x). - Benedict W. J. Irwin, Aug 13 2016

#13 by Benedict W. J. Irwin at Sat Aug 13 14:05:11 EDT 2016
FORMULA

G.f.: 1/8*(2/q^2 -2 + 1/p - 1/q + 2*sqrt(p^2-2*x)/sqrt(q^2+2*x) - sqrt(2)*sqrt(1 + 2*p*q)/(p*q)), where p=sqrt(1+4x) and q=sqrt(1-4x). - Benedict W. J. Irwin, Aug 13 2016

#12 by Benedict W. J. Irwin at Sat Aug 13 14:02:33 EDT 2016
FORMULA

G.f.: 1/8*(2/q^2 -2 + 1/p - 1/q + 2*sqrt(p^2-2*x)/sqrt(q^2+2*x) - sqrt(2)*sqrt(1 + p*q)/(p*q)), where p=sqrt(1+4x) and q=sqrt(1-4x). - Benedict W. J. Irwin, Aug 13 2016

MATHEMATICA

Rest[CoefficientList[Series[1/8(-2+2/(1-4x)-1/Sqrt[1-4x]+1/Sqrt[1+4x]+2/Sqrt[-1+2/(1+2x)]-Sqrt[1+Sqrt[1-16x^2]]/Sqrt[1/2-8x^2]), {x, 0, 20}], x]] (* Benedict W. J. Irwin, Aug 13 2016 *)

STATUS

approved

editing

#11 by Jon E. Schoenfield at Thu Jul 30 21:51:22 EDT 2015
STATUS

editing

approved

#10 by Jon E. Schoenfield at Thu Jul 30 21:51:20 EDT 2015
FORMULA

2a(n)=) = 2^(2n-1)-) - binomial(2n-1, n-1)+) + binomial(n-1, floor(n/2)).

MATHEMATICA

f[n_] := (2^(2n - 1) - Binomial[2n - 1, n - 1] + Binomial[n - 1, Floor[n/2]])/2; Table[ f[n], {n, 24}] (from _}] (* _Robert G. Wilson v_, Mar 24 2005) *)

STATUS

approved

editing

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Last modified August 18 11:16 EDT 2024. Contains 375265 sequences. (Running on oeis4.)