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C. Dement, Table of n, a(n) for n = 0..10000

a[0] = b[0] = 1;

f[n_] := Sign[n]*Mod[n, 2];

a[n_] := a[n] = (1/2)*(a[n-1] - 3*b[n-1]) + 3*f[(1/2)*(a[n-1] + b[n-1])] + f[(1/2)*(a[n-1] - 3*b[n-1])] + 1;

b[n_] := b[n] = (1/2)*(a[n-1] + b[n-1]) + 1;

A108620 = Table[(a[n] + 3*b[n])/2, {n, 0, 100}] (* Jean-François Alcover, Feb 25 2015, after Benoit Jubin *)

Floretion Algebra Multiplication Program, FAMP Code: 1vessum(*)seq[ + .5'i + .5'j + .5'k + .5e]

Cf. A108618, A108619.

Sequence in context: A079536 A058923 A107500 * A070512 A156346 A156283

Adjacent sequences: A108617 A108618 A108619 * A108621 A108622 A108623

easy,sign,look

Creighton Dement, Jun 22 2005

approved