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Search: id:A003128
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| A003128 |
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Number of driving-point impedances of an n-terminal network.
(Formerly M4210)
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+0
8
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| 0, 0, 1, 6, 31, 160, 856, 4802, 28337, 175896, 1146931, 7841108, 56089804, 418952508, 3261082917, 26403700954, 221981169447, 1934688328192, 17454004213180, 162765041827846, 1566915224106221, 15553364227949564, 159004783733999787, 1672432865100333916
(list; graph; listen)
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OFFSET
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0,4
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
J. Riordan, The number of impedances of an n-terminal network, Bell Syst. Tech. J., 18 (1939), 300-314.
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LINKS
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N. J. A. Sloane, Table of n, a(n) for n = 0..100
R. Suter, Two analogues of a classical sequence, J. Integer Sequences, Vol. 3 (2000), #P00.1.8.
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FORMULA
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a(n) = (Bell(n)-3*Bell(n+1)+Bell(n+2))/2. - Vladeta Jovovic (vladeta(AT)eunet.rs), Aug 07 2006
a(n+2) = A123158(n,4) . - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Oct 06 2006
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MAPLE
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with(combinat); A000110:=n->sum(stirling2(n, k), k=0..n): f:=n->(A000110(n)-3*A000110(n+1)+A000110(n+2))/2;
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CROSSREFS
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Cf. A000110, A003129, A003130, A039759, A039765 etc.
Sequence in context: A038223 A022034 A047665 this_sequence A058146 A015449 A162475
Adjacent sequences: A003125 A003126 A003127 this_sequence A003129 A003130 A003131
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KEYWORD
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nonn,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Apr 14 2000
Typo in entries corrected by Martin Larsen, Jul 03 2008
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