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A078495
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a(n)=(a(n-1)*a(n-6)+a(n-3)*a(n-4))/a(n-7). Somos-7 variation.
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1
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1, 1, 1, 1, 1, 1, 1, 2, 3, 4, 6, 12, 24, 72, 144, 288, 864, 3456, 10368, 41472, 124416, 497664, 2985984, 17915904, 71663616, 429981696, 2579890176, 20639121408, 185752092672, 1486016741376, 8916100448256, 106993205379072
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,8
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REFERENCES
| G. Everest, A. van der Poorten, I. Shparlinski and T. Ward, Recurrence Sequences, Amer. Math. Soc., 2003; see esp. p. 255.
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LINKS
| T. D. Noe, Table of n, a(n) for n=0..100
Index entries for two-way infinite sequences
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FORMULA
| a(n)=144*a(n-6)*a(n-10)/a(n-16).
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PROG
| (PARI) a(n)=if(n<0, a(6-n), if(n<7, 1, (a(n-1)*a(n-6)+a(n-3)*a(n-4))/a(n-7)))
(PARI) a(n)=2^(b(n-9)+b(n-7))*3^b(n-8); b(n)=(n^2+10*n+1-n%2*13)\60+1
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CROSSREFS
| Cf. A025795(n)=b(n), A006723.
Sequence in context: A018343 A102462 A018369 * A161701 A038504 A018405
Adjacent sequences: A078492 A078493 A078494 * A078496 A078497 A078498
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KEYWORD
| nonn,easy,nice
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AUTHOR
| Michael Somos, Nov 26 2002
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