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Search: id:A086836
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| A086836 |
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On a 3 X 3 board, number of distinct positions of n digits (modulo rotation/reflection)). |
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+0
1
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OFFSET
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1,1
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COMMENT
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Sequence is finite by definition. Last two numbers are naturally 8 times less than 9!, the total number of 3 X 3 squares (not taking into account symmetries).
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FORMULA
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a(n) = 1/8*([9]_n+4*[3]_n+3*[1]_n) = 3/8*(967680-1145424*n+705596*n^2-256796*n^3+59649*n^4-8936*n^5+834*n^6-44*n^7+n^8)/GAMMA(10-n), where [m]_n=m*(m-1)*...*(m-n+1) is falling factorial. - Vladeta Jovovic (vladeta(AT)Eunet.yu), Aug 10 2003
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EXAMPLE
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a(1)=3 because there are 3 distinct (corner, side or central ) cells which can be occupied by 1 digit
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CROSSREFS
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Cf. A087074.
Sequence in context: A109577 A007017 A082987 this_sequence A074513 A007871 A058790
Adjacent sequences: A086833 A086834 A086835 this_sequence A086837 A086838 A086839
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KEYWORD
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easy,nonn,fini,full
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AUTHOR
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Zak Seidov (zakseidov(AT)yahoo.com), Aug 08 2003
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