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A003130 Impedances of an n-terminal network.
(Formerly M4873)
2
1, 12, 157, 1750, 17446, 164108, 1505099, 13720902, 125782441, 1167813944, 11029947952, 106273227216, 1046320856673, 10537366304920, 108606982421301, 1145873284492738, 12375688888657414, 136802023177966948, 1547385154016264531 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,2

REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Table of n, a(n) for n=2..20.

J. Riordan, The number of impedances of an n-terminal network, Bell Syst. Tech. J., 18 (1939), 300-314.

FORMULA

a(n) = A003128(n) + 2 * A003129(n) + U(n) where U(n) = sum(u(n) * Stirling2(n, k), k=2..n) and u(n) = (20(n)_4 + 10(n)_5 + (n)_6) / 8 where (n)_k = n * (n - 1) * ... * (n - k + 1) denotes the falling factorial. - Sean A. Irvine, Feb 03 2015

CROSSREFS

Cf. A003128, A003129.

Sequence in context: A110216 A218839 A036276 * A015000 A220225 A213376

Adjacent sequences:  A003127 A003128 A003129 * A003131 A003132 A003133

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Sean A. Irvine, Feb 03 2015

STATUS

approved

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Last modified January 20 23:20 EST 2019. Contains 319343 sequences. (Running on oeis4.)