A109851 a(1) = 1, a(2) = 2; for n > 2, sum of absolute differences of all combinations of pairs of previous terms.

1, 2, 1, 2, 4, 14, 74, 494, 3854, 34094, 336494, 3662894, 43579694, 562498094, 7827355694, 116800219694, 1860366043694, 31500985051694, 565032127195694, 10702123827931694, 213443957842651694, 4471022472151771694, 98137749786952411694, 2252472478027367131694

Offset

1,2

Comments

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

Links

Robert Israel, Table of n, a(n) for n = 1..450

Formula

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

Example

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)).

Maple

A[1]:= 1: A[2]:= 2: A[3]:= 1:
for n from 4 to 100 do
  A[n]:= A[n-1] + add(abs(A[n-1]-A[k]), k=1..n-2);
od:
convert(A, list); # Robert Israel, Oct 23 2024

Crossrefs

Sequence in context: A095067 A225564 A032259 * A371136 A245841 A011404

Adjacent sequences: A109848 A109849 A109850 * A109852 A109853 A109854

Keyword

nonn

Author

Amarnath Murthy, Jul 06 2005

Extensions

More terms from Joshua Zucker, May 04 2006

Corrected by Charles R Greathouse IV, Jun 08 2015

Status

approved