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Conference rusure::math

Title:Mathematics at DEC
Moderator:RUSURE::EDP
Created:Mon Feb 03 1986
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:2083
Total number of notes:14613

251.0. "mapping sequence" by SPRITE::OSMAN () Wed Apr 03 1985 12:12

What's the next number in this sequence:

	9, 16, 30, 90, 20, 2, 225, . . .

T.RTitleUserPersonal
Name
DateLines
251.1FUTBAL::GILBERTWed Apr 03 1985 21:071
14
251.2RAINBO::GRANTFri Apr 05 1985 19:0911
Proof is simple:

Lemma 1:  All puzzles in this notes file since February are of two types:
 1. They are related to permutations of (1...N), or
 2. The answer is 14.

Since the sequence doesn't seem to be related to permutations,
the answer must be 14.

QED.

251.3SPRITE::OSMANMon Apr 08 1985 17:195
Well, I must admit I find no flaw in your proof.

Hence I must conclude the map is wrong, since it doesn't say 14 is the next
number.

251.4SPRITE::OSMANFri Apr 12 1985 11:475
Hint:

	As is often good advice when lost, look on the ___.

251.5LATOUR::JMUNZERFri Apr 12 1985 13:111
4 (another square).  Gulp!
251.6SPRITE::OSMANFri Apr 12 1985 16:562
I'm not quite sure whether you've caught on or not.  Just to assure me,
if you think 4 comes next, what's after that ?
251.7LATOUR::JMUNZERSat Apr 13 1985 13:011
3 (another square root)
251.8SPRITE::OSMANTue Apr 16 1985 11:288
Yes, folks I believe this person has caught on !  Congratulations.

My idea for what comes after 225 is indeed 3.  However, as pointed out,
4 can be easily argued for insertion.  I didn't quite agree with 4,
merely because it shares an exit with 225.

/Eric

251.9KOBAL::GILBERTTue Apr 16 1985 11:501
Three?!  All the other numbers in 251.0 take the form of either n^2 or n(n+1).
251.10SPRITE::OSMANFri Apr 19 1985 16:245
BIG hint (for those that haven't yet figured out that MAP in this problem
refers to one of Boston):

	Drive northward on rte. 128 !

251.11I've been had!!!!KIRK::KOLKERWed Jun 03 1987 18:445
    argh!!!!!!
    38,93,114,62... oh excrement!
    o.k. wiseperson, do this well know series:
    14,18,23,34,42,...
    
251.12okay to insert?VINO::JMUNZERThu Jun 04 1987 10:123
        14,18,23,28,34,42,... ?
    
	John