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Search: id:A082430
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| A082430 |
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a(1)=1, a(n)=n*(a(n-1)+a(n-2)+...+a(2)+a(1)) + 4. |
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+0
1
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| 1, 6, 25, 132, 824, 5932, 48444, 442916, 4484524, 49828044, 602919332, 7892762164, 111156400476, 1675896499484, 26934050884564, 459674468429892, 8302870086014924, 158242935756990316, 3173649989348528004
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OFFSET
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1,2
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COMMENT
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More generally if m is an integer and a(1)=1, a(n)=n*(a(n-1)+a(n-2)+...+a(2)+a(1)) + m then a(n) has a closed form formula as : a(n)=floor/ceil(n*r(m)*n!) where r(m)=frac(e*m) + 0 or + 1/2 or -1/2 + integer. Ex : r(10)=frac(10*e)+1/2+2; r(12)=frac(12*e)-1/2+3; r(15)=frac(15*e)+3; r(18)=frac(18*e)-1/2+4 ...
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FORMULA
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for n>=2 a(n) = ceiling(n*(19/2-4e)*n!)
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CROSSREFS
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Cf. A007808, A074143.
Adjacent sequences: A082427 A082428 A082429 this_sequence A082431 A082432 A082433
Sequence in context: A120758 A099359 A073967 this_sequence A136593 A012293 A012594
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KEYWORD
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nonn
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Apr 24 2003
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