OFFSET
1,2
COMMENTS
Suggested by Problem 401 of the All-Soviet-Union Mathematical Competitions 1961-1986. Two different links are available for this collection.
LINKS
Mauro Fiorentini, Further comments
Vladimir A. Pertsel, Problems of the All-Soviet-Union Mathematical Competitions 1961-1986
FORMULA
From A.H.M. Smeets, Feb 25 2022: (Start)
a(n) > 2*a(n-1). Proof: Let x, y be the numbers in the second last row, then x >= a(n-1), y >= a(n-1) and x != y, so a(n) = x + y > 2*a(n-1).
It seems that a(n) > (4/3)*(2*a(n-1)-a(n-2)). (End)
EXAMPLE
Solutions for n = 1, 2, ... are:
1;
1, 2;
2, 1, 4;
4, 1, 2, 7;
7, 2, 1, 4, 6;
8, 6, 1, 3, 2, 10;
...
CROSSREFS
KEYWORD
nonn,nice
AUTHOR
EXTENSIONS
More terms from the author, Jul 03 2001
STATUS
approved