A058966 a(3) = 1, otherwise a(n) = n*2^(n-3) - 2^(n-2) - 2.

1, 2, 10, 30, 78, 190, 446, 1022, 2302, 5118, 11262, 24574, 53246, 114686, 245758, 524286, 1114110, 2359294, 4980734, 10485758, 22020094, 46137342, 96468990, 201326590, 419430398, 872415230, 1811939326, 3758096382, 7784628222, 16106127358, 33285996542, 68719476734

Offset: 3

Author

N. J. A. Sloane, Jan 14 2001

Keywords

• nonn
• easy

References

• B. Elspas, The theory of multirail cascades, in A. Mukhopadhyay, ed., Recent Developments in Switching Theory, Ac. Press, 1971, Chap. 8, see esp. p. 361 (S_1(n)).

Links

• Harry J. Smith, Table of n, a(n) for n = 3...200
• Index entries for linear recurrences with constant coefficients, signature (5,-8,4).

Programs

Mathematica

Join[{1},Table[n*2^(n-3)-2^(n-2)-2,{n,4,40}]] (* or *) LinearRecurrence[ {5,-8,4},{1,2,10,30},40] (* Harvey P. Dale, Dec 22 2019 *)

PARI

a(n) = { abs(n*2^(n-3)-2^(n-2)-2) } \\ Harry J. Smith, Jun 24 2009

Formula

From Colin Barker, Mar 23 2012: (Start)

a(n) = 5*a(n-1)-8*a(n-2)+4*a(n-3) for n>6.

G.f.: x^3*(1-3*x+8*x^2-8*x^3)/((1-x)*(1-2*x)^2). (End)