A073720 Let b(1) = 1, b(k+1) = b(k) - k*trunc(k/b(k)+1), where trunc(x) = floor(x) if x>= 0, trunc(x) = ceiling(x) otherwise. Sequence a(n) gives the successive absolute values taken by b(k).

1, 11, 58, 293, 1468, 7343, 36718, 183593, 917968, 4589843, 22949218, 114746093, 573730468, 2868652343, 14343261718, 71716308593, 358581542968, 1792907714843, 8964538574218, 44822692871093, 224113464355468

Offset: 1

Author

Benoit Cloitre, Aug 30 2002

Keywords

• nonn

Formula

It appears that for n>1 a(n)=( 47*5^(n-2)-3 )/4 and if 2*a(n-1)+1 < k < 2*a(n)+1, then b(k)= -a(n), if k = 2*a(n)+1 b(k)= +a(n).

Empirical g.f.: -x*(3*x^2-5*x-1) / ((x-1)*(5*x-1)). - Colin Barker, Jun 17 2013