login
a(1) = 1, a(2) = 2; for n > 2, sum of absolute differences of all combinations of pairs of previous terms.
1

%I #13 Oct 23 2024 16:32:41

%S 1,2,1,2,4,14,74,494,3854,34094,336494,3662894,43579694,562498094,

%T 7827355694,116800219694,1860366043694,31500985051694,565032127195694,

%U 10702123827931694,213443957842651694,4471022472151771694,98137749786952411694,2252472478027367131694

%N a(1) = 1, a(2) = 2; for n > 2, sum of absolute differences of all combinations of pairs of previous terms.

%C The final digits approach a limit. That is, after the first few terms, all the terms end in 70194710743368411694 and as more terms go by, even more digits remain constant. - _Joshua Zucker_, May 04 2006

%H Robert Israel, <a href="/A109851/b109851.txt">Table of n, a(n) for n = 1..450</a>

%F a(n+1) = a(n) + sum [ absolute{a(n) - a(k)}, k = 1 to n].

%e 14 is the next term after 4= a(5), 14 = 4 + abs(4-a(1)) + abs(4-a(2)) + abs( 4-a(3)) + abs(4-a(4)).

%p A[1]:= 1: A[2]:= 2: A[3]:= 1:

%p for n from 4 to 100 do

%p A[n]:= A[n-1] + add(abs(A[n-1]-A[k]),k=1..n-2);

%p od:

%p convert(A,list); # _Robert Israel_, Oct 23 2024

%K nonn

%O 1,2

%A _Amarnath Murthy_, Jul 06 2005

%E More terms from _Joshua Zucker_, May 04 2006

%E Corrected by _Charles R Greathouse IV_, Jun 08 2015