Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

**anonimnystefy****Real Member**- From: The Foundation
- Registered: 2011-05-23
- Posts: 15,518

We could continue in your thread in Computer Math about diophantine equations.

Here lies the reader who will never open this book. He is forever dead.

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,219

That is not what I meant. GF's are rather obscure and not taught. He/she will probably expect a solution in terms of ncr's.

**In mathematics, you don't understand things. You just get used to them.Of course that result can be rigorously obtained, but who cares?Combinatorics is Algebra and Algebra is Combinatorics.**

**Online**

**Batman****Guest**

What you could do is say the kids got a, b, c, d, d (the twins each got the same) and then seek quadruples satisfiing a+b+c+2d=13 than try each value of d.

d=0: 13 candies 3 kids place dividers in ccccccccccccc (c for CANDY!) and see the number of ways we can put the 3 dividers (3 kids left) so 15 choose 2 = 105

d=1: same, 13 choose 2 = 78

d=2: same logic, 11 choose 2 = 55

d=3: ditto I stop saying same 9 choose 2 = 36

d=4: 7 choose 2 = 21

d=5: 5 choose 2 = 10

d=6: 3 choose 2 = 3

105+78+55+36+21+10+3=308

I got 308

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,219

Hi;

Welcome to the forum, 308 is the correct answer.

**In mathematics, you don't understand things. You just get used to them.Of course that result can be rigorously obtained, but who cares?Combinatorics is Algebra and Algebra is Combinatorics.**

**Online**

**anonimnystefy****Real Member**- From: The Foundation
- Registered: 2011-05-23
- Posts: 15,518

That looks like something that would please the OP.

By the way, I just though of a twist to the puzzle to make it just a bit harder.

Here lies the reader who will never open this book. He is forever dead.

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

Offline

bobbym wrote:

Yes, I see that.

How about the recurrence:

with a(0)=1,a(1)=3

This is for what?

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'Humanity is still kept intact. It remains within.' -Alokananda

**Online**

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,219

For post #1.

**In mathematics, you don't understand things. You just get used to them.Of course that result can be rigorously obtained, but who cares?Combinatorics is Algebra and Algebra is Combinatorics.**

**Online**