login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A007456 Days required to spread gossip to n people. 7
0, 1, 3, 2, 4, 3, 4, 3, 5, 4, 5, 4, 5, 4, 5, 4, 6, 5, 6, 5, 6, 5, 6, 5, 6, 5, 6, 5, 6, 5, 6, 5, 7, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 6, 8, 7, 8, 7, 8, 7, 8, 7, 8, 7, 8, 7, 8, 7, 8, 7, 8, 7, 8, 7, 8, 7, 8 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

On first day, each gossip has his own tidbit. On each successive day, disjoint pairs of gossips may share tidbits (over the phone). After a(n) days, all gossips have all tidbits.

a(A240277(n)) = n and a(m) < n for m < A240277(n). - Reinhard Zumkeller, Apr 03 2014

REFERENCES

D. Shasha, Gossiping Defenders, The Puzzling Adventures of Dr. Ecco, pp. 62-4;156 W. H. Freeman NY 1988.

LINKS

T. D. Noe, Table of n, a(n) for n = 1..10000

C. Kenneth Fan, Bjorn Poonen and George Poonen, How to spread rumors fast, Mathematics Magazine 70 (Feb, 1997), pp. 40-42.

I. Peterson, Spreading Rumors, MathLand, March 17, 1997.

FORMULA

a(1) = 0; a(n) = [ log_2 (n-1) ] + ((n-2) mod 2) + 1 (n >= 2)

G.f.: 1/(1-z)*(sum(k>=0, z^(2^k))+1/(1+z))-1. - Ralf Stephan, Apr 06 2003

MATHEMATICA

Join[{0}, Table[Floor[Log[2, n - 1]] + Mod[n - 2, 2] + 1, {n, 2, 100}]] (* T. D. Noe, Mar 16 2012 *)

PROG

(Haskell)

a007456 1 = 0

a007456 n = a000523 (n - 1) + mod n 2 + 1

-- Reinhard Zumkeller, Apr 03 2014

CROSSREFS

Cf. A160464, A043529.

Cf. A000523.

Sequence in context: A247190 A243289 A134559 * A119707 A052938 A140114

Adjacent sequences:  A007453 A007454 A007455 * A007457 A007458 A007459

KEYWORD

nonn,nice,easy

AUTHOR

Alex Graesser (AlexG(AT)sni.co.za)

EXTENSIONS

More terms from David W. Wilson

Formulae corrected by Johannes W. Meijer, May 15 2009

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified December 13 00:17 EST 2017. Contains 295954 sequences.