The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A158618 Number of gates in Ladner-Fisher prefix circuit 1
 0, 1, 2, 4, 5, 7, 9, 12, 13, 15, 17, 20, 22, 25, 27, 31, 32, 34, 36, 39, 41, 44, 46, 50, 52, 55, 57, 61, 64, 67, 69, 74, 75, 77, 79, 82, 84, 87, 89, 93, 95, 98, 100, 104, 107, 110, 112, 117, 119, 122, 124, 128, 131, 134, 136, 141, 143, 147, 149, 153 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 REFERENCES D.E. Knuth, The Art of Computer Programming, Volume 4, Fascicle 0. See exercise 7.1.2.36 and solution. R.E. Ladner and M.J. Fischer, Parallel Prefix Computation, JACM 27 (1980) 831-838. LINKS Andrew Howroyd, Table of n, a(n) for n = 1..1000 FORMULA With s = floor(n/2), r = ceiling(n/2) and a(1) = b(1) = 0, recurrence relation is a(n) = s + b(r) + a(s), b(n) = 2s-1 + a(r). If n = 2^m then a(n) = 4n+1 - Fibonacci(m+5). PROG (PARI) b(n)={if(n<=1, 0, 2*(n\2) - 1 + a((n+1)\2))} a(n)={if(n<=1, 0, n\2 + b((n+1)\2) + a(n\2))} \\ Andrew Howroyd, Mar 28 2020 CROSSREFS Sequence in context: A140205 A140206 A007818 * A000788 A053039 A286753 Adjacent sequences:  A158615 A158616 A158617 * A158619 A158620 A158621 KEYWORD nonn AUTHOR Frank Ruskey, Mar 22 2009 EXTENSIONS Terms a(41) and beyond from Andrew Howroyd, Mar 28 2020 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified June 22 00:39 EDT 2021. Contains 345367 sequences. (Running on oeis4.)