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Search: id:A120743
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| A120743 |
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a(n) = (1/2)*(1+3*I)^n + (1/2)*(1-3*I)^n. |
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+0
1
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| 1, -8, -26, 28, 316, 352, -2456, -8432, 7696, 99712, 122464, -752192, -2729024, 2063872, 31417984, 42197248, -229785344, -881543168, 534767104, 9884965888, 14422260736, -70005137408, -284232882176, 131585609728, 3105500041216
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Comment from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 15 2007: These are the row sums of the triangle A013610 after every 2nd column is deleted, then every 2nd column reversed in sign, creating an intermediate irregular triangle with entries C(n,2*k)*(-9)^k, k=1..n/2:
1,
1, -9;
1, -27;
1, -54, 81;
1, -90, 405;
1, -135, 1215, -729;
1, -189, 2835, -5103;
1, -252, 5670, -20412, 6561;
1, -324, 10206, -61236, 59049;
1, -405, 17010, -153090, 295245, -59049;
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FORMULA
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a(n) = 2*a(n-1) - 10*a(n-2), G.f. (1-10*x)/(10*x^2-2*x+1)
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PROGRAM
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Floretion Algebra Multiplication Program, FAMP Code: 2tesseq[A*B] with A = + 1.5i' + .5j' + .5k' + .5e and B = 'ji' + e
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CROSSREFS
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Cf. A006495.
Sequence in context: A060718 A060743 A029617 this_sequence A063560 A069952 A031085
Adjacent sequences: A120740 A120741 A120742 this_sequence A120744 A120745 A120746
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KEYWORD
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easy,sign
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AUTHOR
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Creighton Dement (creighton.k.dement(AT)uni-oldenburg.de), Jun 11 2007
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