Since there hasn’t been a sequence yet on the other thread dealing with numbers as numbers (as opposed to stand-ins for subway stops, speech patterns, and whatnot), I thought I’d start a thread which restricted the number sequences to their numerical properties.
Whoever guesses the next number in one sequence correctly (with explanation) gets to provide the next one.
Let’s lead off with something reasonably lite:
1,5,13,29…
I think you mean powers of two.
alternate answer = 47
This will work if, and only if, you consider 1 to be a prime number (which it really isn’t). The sequence goes like this: name a prime number, skip 1 prime #, name another prime #, skip 2 prime #'s, name the next prime #, skip 3 prime #'s, etc.
Damn, wait, if you consider 1 a prime number, then 2 would have to be considered prime as well, which throws the whole thing off. Oh, well. It holds if you start at five and skip two primes.
2 is prime.
I came up with 61 also, but from a simpler formula: Each number is 3 plus the previous number doubled.
3+21 = 5
3+25 = 13
3+213 = 29
3+229 = 61
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2 is prime. **
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yep, you’re right. Would have worked if FTfirefly had replaced 1 with 2. Oh well. Who gets to post the next series?
Even though I didn’t post the answer first, I got it without looking at those who did. Therefore, since no one has presented another sequence, I will:
7,24,58,126
Too easy: 262
Double the number and add 10
Give me a second to think up the next series.
O.K. a wee bit harder:
2,5,24,120
You may find this site interesting: http://www.research.att.com/~njas/sequences/index.html
Interesting or not, it didn’t give the answer I was looking for. The formula is much simpler than whatever the Hades “Self-complementary 2-multigraphs with loops on n nodes.” is.
Wrong. You actually add five to the number, then multiply by two.
That’s a joke right? I’m a little slow today. 2(X + 5) = 2X + 10