This site is supported by donations to The OEIS Foundation.



Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A095912 Variant of the pay-phone sequence A095236. Here a slot at the end of the row is always preferred over a slot sandwiched immediately between two used slots. 2
1, 2, 4, 6, 12, 28, 104, 152, 528, 2208, 9120, 23616, 130944, 278784, 1635840, 14181120, 32186880, 116674560, 1262039040, 2443714560, 58920099840, 161981890560, 1416311930880, 7700720025600, 120779469619200 (list; graph; refs; listen; history; text; internal format)



Max Alekseyev, Table of n, a(n) for n = 1..100


Example: there are 5 payphones. First arrival may choose any; he selects phone #2. Next arrival must take the furthest away, #5. Next arrival must take either of #3 or #4 (since both have a neighbor on one side and a vacant slot on the other); he chooses #3. Next arrival must take #1 (because end slots are preferred over "sandwiched" slots), leaving #4 for the last arrival. The permutation (25314) is one of a(5)=10 that satisfy the requirements.


Cf. A095236, A095239, A095240, A095923.

Sequence in context: A087997 A177905 A118405 * A143474 A261341 A220423

Adjacent sequences:  A095909 A095910 A095911 * A095913 A095914 A095915




Jon Wild, Jul 13 2004


Corrected and extended by Don Reble, Jul 15 2004



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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 10 14:27 EST 2019. Contains 329896 sequences. (Running on oeis4.)