A073720 - OEIS

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

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..21.

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

CROSSREFS

Sequence in context: A290360 A359719 A356039 * A257364 A141302 A139872

Adjacent sequences: A073717 A073718 A073719 * A073721 A073722 A073723

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Aug 30 2002

STATUS

approved