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Search: id:A121081
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| A121081 |
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Number of partitions of n into parts with at most one 1 and at most one 2. |
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+0
3
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| 1, 1, 2, 2, 3, 5, 6, 8, 11, 14, 18, 24, 30, 38, 49, 61, 76, 96, 118, 146, 181, 221, 270, 331, 401, 486, 589, 709, 852, 1025, 1225, 1463, 1746, 2075, 2463, 2922, 3453, 4077, 4808, 5656, 6644, 7798, 9130, 10678, 12475, 14547, 16942, 19714, 22898, 26570, 30798
(list; graph; listen)
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OFFSET
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1,3
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FORMULA
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a(n) = A121659(n) + A008483(n-3) for n>2. - Reinhard Zumkeller (reinhard.zumkeller(AT)lhsystems.com), Aug 14 2006
G.f.: (1+x)*(1+x^2)/Product_{k>=3} 1-x^k. - Vladeta Jovovic (vladeta(AT)Eunet.yu), Aug 13 2006
a(n) = A000041(n)-A000041(n-2)-A000041(n-4)+A000041(n-6), n>5. - Vladeta Jovovic (vladeta(AT)Eunet.yu), Aug 13 2006
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EXAMPLE
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a(8)=#{8,7+1,6+2,5+3,5+2+1,4+4,4+3+1,3+3+2}=8;
a(9)=#{9,8+1,7+2,6+3,6+2+1,5+4,5+3+1,4+4+1,4+3+2,3+3+3,3+3+2+1}=11.
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CROSSREFS
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Cf. A027336.
Sequence in context: A035631 A050046 A052337 this_sequence A118399 A076571 A084783
Adjacent sequences: A121078 A121079 A121080 this_sequence A121082 A121083 A121084
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KEYWORD
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nonn
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AUTHOR
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Reinhard Zumkeller (reinhard.zumkeller(AT)lhsystems.com), Aug 11 2006
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