%I A028307
%S A028307 1,3,8,20,43,98,212,465,1000,2144,4497,9504,19872,41455,85356,
%T A028307 178630,363467,757085,1541998,3183600,6515066,13357593,27432649,
%U A028307 55914902,114683858,233517515,478061719,972479046,1986013932
%N A028307 Form a triangle with n numbers in top row; all other numbers are the 
               sum of their parents. E.g.: 4 1 2 7; 5 3 9; 8 12; 20. The numbers 
               must be positive and distinct and the final number is to be minimized. 
               Sequence gives final number.
%C A028307 Suggested by Problem 401 of the All-Soviet-Union Mathematical Competitions 
               1961-1986. Two different links are available for this collection.
%H A028307 Mauro Fiorentini, <a href="a028307.txt">Further comments</a>
%H A028307 Vladimir A. Pertsel (voldemar(AT)wiscon.weizmann.ac.il), <a href="http:/
               /members.tripod.com/~PertselV/RusMath.html">Problems of the All-Soviet-Union 
               Mathematical Competitions 1961-1986</a>
%e A028307 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...
%Y A028307 Sequence in context: A143785 A135565 A139488 this_sequence A027298 A000236 
               A109327
%Y A028307 Adjacent sequences: A028304 A028305 A028306 this_sequence A028308 A028309 
               A028310
%K A028307 nonn,nice
%O A028307 1,2
%A A028307 Mauro Fiorentini (mfiorentini(AT)etnoteam.it)
%E A028307 More terms from the author, Jul 03, 2001