[seqfan] Filling a triangle with numbers
njasloane at gmail.com
Fri Jul 6 15:51:07 CEST 2012
I heard this problem in Hungary recently:
How many ways are there to arrange the numbers 1 through n(n+1)/2 in
a triangle so that each term is between the two numbers
immediately below it (and each row is increasing)?
I get a(1)=a(2)=1, a(3)=2, a(4)=6?
The only related sequences I can find in the OEIS are A064049, A064059,
which are different. However, it is quite likely this is a well-studied
Also, what if one omits the clause in parentheses in the definition?
More information about the SeqFan