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A106603 a(n) = - 2*a(n-1) - 8*a(n-3), a(0) = 1, a(1) = 1, a(2) = -2. 1
1, 1, -2, -4, 0, 16, 0, 0, -128, 256, -512, 2048, -6144, 16384, -49152, 147456, -425984, 1245184, -3670016, 10747904, -31457280, 92274688, -270532608, 792723456, -2323644416, 6811549696, -19964887040, 58518929408, -171530256384, 502779609088, -1473710653440, 4319663357952 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Were only the first few terms of the sequence taken into account, it would appear that the sequence consists only of 0 and powers of 2. Upon dividing out the powers of 2 from each term of the sequence, one sees that, actually, a(n) = c(n)*d(n) with c = (1, 1, -1, -1, 0, 1, 0, 0, 1, 1, 1, 1, 3, 1, 3, 3, 13, 19, 7, 41, 15, 11, 129, 189,) and d = (2^0, 2^0, 2, 2^2, 0, 2^4, 0, 0, 2^7, 2^8, 2^9, 2^(11), 2^(11), 2^(14), 2^(14), 2^(14), 2^(15), 2^(16), 2^(19), 2^(18), 2^(21), 2^(23), 2^(21), 2^(22),).

LINKS

Table of n, a(n) for n=0..31.

FORMULA

G.f. (3*x+1)/(8*x^3+1+2*x)

PROG

Floretion Algebra Multiplication Program, FAMP Code: 1basej[A*B] with A = + .5'i - .5'k + .5i' - .5k' - 2'jj' - .5'ij' - .5'ji' - .5'jk' - .5'kj' and B = + .5'i + .5'j + .5i' + .5j' + .5'kk' + .5'ij' + .5'ji' + .5e

CROSSREFS

Sequence in context: A073451 A078022 A203850 * A059057 A196225 A127511

Adjacent sequences:  A106600 A106601 A106602 * A106604 A106605 A106606

KEYWORD

easy,sign

AUTHOR

Creighton Dement, May 10 2005

STATUS

approved

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Last modified March 25 01:30 EDT 2017. Contains 284036 sequences.