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Search: a280059 -id:a280059
Displaying 1-1 of 1 result found. page 1
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A181773 Molecular topological indices of the cocktail party graphs. +10
1
0, 48, 240, 672, 1440, 2640, 4368, 6720, 9792, 13680, 18480, 24288, 31200, 39312, 48720, 59520, 71808, 85680, 101232, 118560, 137760, 158928, 182160, 207552, 235200, 265200, 297648, 332640, 370272, 410640 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
a(n) is the number of 2 X 2 matrices (all four elements distinct) having entries in {-n,...,0,...,n} with determinant equal to the permanent. - Indranil Ghosh, Dec 25 2016
LINKS
Table of n, a(n) for n=1..30.
Eric Weisstein's World of Mathematics, Molecular Topological Index
Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1).
FORMULA
a(n) = 8*(n-1)*n*(2n-1).
a(n) = 16*A059270(n-1).
G.f.: 48*x^2*(x+1)/(x-1)^4. - Colin Barker, Oct 17 2012
a(n) = 48*A000330(n-1). - R. J. Mathar, Jan 04 2017
From Omar E. Pol, Jan 05 2017: (Start)
a(n) = 24*A006331(n-1) = 12*A002492(n-1) = 8*A055112(n-1).
a(n) = 2*A069074(n-2), n >= 2. (End)
MAPLE
A181773:=n->8*(n-1)*n*(2*n-1): seq(A181773(n), n=1..50); # Wesley Ivan Hurt, Apr 11 2017
CROSSREFS
Cf. A280059 (2 X 2 matrices, elements can be repeated).
KEYWORD
nonn,easy
AUTHOR
Eric W. Weisstein, Jul 10 2011
STATUS
approved
page 1

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Last modified August 29 12:15 EDT 2024. Contains 375517 sequences. (Running on oeis4.)