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Search: id:A090991
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| A090991 |
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Number of meaningful differential operations of the n-th order on the space R^6. |
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+0
4
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| 6, 10, 16, 26, 42, 68, 110, 178, 288, 466, 754, 1220, 1974, 3194, 5168, 8362, 13530
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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B. Malesevic: Some combinatorial aspects of differential operation composition on the space R^n, Univ. Beograd, Publ. Elektrotehn. Fak., Ser. Mat. 9 (1998), 29-33.
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LINKS
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Tanya Khovanova, Recursive Sequences
B. Malesevic, Some combinatorial aspects of differential operation composition on the space R^n
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FORMULA
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a(k+4)=3*a(k+2)-a(k), a(k)=2*Fib(k+3)
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MAPLE
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NUM := proc(k :: integer) local i, j, n, Fun, Identity, v, A; n := 6; # <- DIMENSION Fun := (i, j)->piecewise(((j=i+1) or (i+j=n+1)), 1, 0); Identity := (i, j)->piecewise(i=j, 1, 0); v := matrix(1, n, 1); A := piecewise(k>1, (matrix(n, n, Fun))^(k-1), k=1, matrix(n, n, Identity)); return(evalm(v&*A&*transpose(v))[1, 1]); end:
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CROSSREFS
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Cf. A055389, A068922, A078642, A090989-A090995.
Essentially the same as A006355.
Adjacent sequences: A090988 A090989 A090990 this_sequence A090992 A090993 A090994
Sequence in context: A114975 A079329 A020741 this_sequence A019533 A053301 A049302
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KEYWORD
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nonn
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AUTHOR
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Branko Malesevic (malesevic(AT)kiklop.etf.bg.ac.yu), Feb 29 2004
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