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A108349
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Main diagonal of Fibonacci-type array in which each term is equal to the term above multiplied by the term to the left.
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1
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OFFSET
| 1,3
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COMMENTS
| a(9) has 178 digits. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 26 2008]
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FORMULA
| T(x, y) = T(x, y-1) * T(x-1, y) T(x, 1) = T(x-2, 1) + T(x-1, 1) T(1, 1) = 1 Direct Formula is T(x, x) for x = {1, 2, 3, 4...}
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EXAMPLE
| a(4) = T(4,4) = 24; 24 = 2 * 12 = (1 * 2) * (2 * 6) = (1 * 2) * (2 * (2 * 3)) See chart:
1 1 2 3 5 ... (Fibonacci)
- 1 2 6 15 T(x, 2)
- - 2 12 90 T(x, 3)
- - - 24 1080 T(x, 4)
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MAPLE
| A108349T := proc(n, i) option remember ; if n = 1 then combinat[fibonacci](i) ; else procname(n-1, i)*procname(n-1, i+1) ; fi; end: A108349 := proc(n) A108349T(n, 1) ; end: for n from 1 to 9 do printf("%d, ", A108349(n)) ; od: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 26 2008]
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CROSSREFS
| Sequence in context: A152687 A062716 A137888 * A000722 A098679 A123851
Adjacent sequences: A108346 A108347 A108348 * A108350 A108351 A108352
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KEYWORD
| nonn,easy
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AUTHOR
| Brock J Nash (Brocknash(AT)wah.midco.net), Aug 17 2008
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EXTENSIONS
| a(6)-a(8) from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 26 2008
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