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A060919
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Number of corners in a 4-sided fractal.
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6
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4, 8, 20, 60, 204, 748, 2860, 11180, 44204, 175788, 701100, 2800300, 11193004, 44755628, 178989740, 715893420, 2863442604, 11453508268, 45813508780, 183252986540, 733009849004, 2932035201708, 11728132418220, 46912512895660
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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LINKS
| Harry J. Smith, Table of n, a(n) for n=1,...,200
H. Bottomley, Illustration of initial terms
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FORMULA
| a(n) =4^n/6+2^n+4/3 =(2^n+2)*(2^n+4)/6 =4*A007581(n-1) =4(a(n-1)-1)-2^n =A028400(n-1)-A002450(n-1)
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PROG
| (PARI) { for (n=1, 200, write("b060919.txt", n, " ", (2^n + 2)*(2^n + 4)/6); ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Jul 14 2009]
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CROSSREFS
| Sequence in context: A203167 A123861 A115099 * A009333 A187010 A086912
Adjacent sequences: A060916 A060917 A060918 * A060920 A060921 A060922
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KEYWORD
| nonn
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AUTHOR
| Henry Bottomley (se16(AT)btinternet.com), Apr 10 2001
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