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Search: id:A066665
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| A066665 |
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a(n) = #{(x,y) | 0<=y<=x<=n and x+y is prime}. |
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+0
1
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| 1, 3, 5, 7, 9, 11, 14, 16, 19, 23, 27, 31, 35, 38, 42, 47, 52, 56, 61, 65, 70, 76, 82, 88, 94, 100, 107, 114, 121, 128, 136, 143, 150, 158, 166, 175, 185, 194, 203, 213, 223, 233, 243, 252, 262, 272, 282, 291, 301, 311, 322, 334, 346
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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a(0) = 0, for n>0: a(n) = a(n-1) + A035250(n).
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EXAMPLE
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a(3)=5, as sums of (1,1), (2,0), (2,1), (3,0) and (3,2) give 5 primes.
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CROSSREFS
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Cf. A000720, A035250.
Adjacent sequences: A066662 A066663 A066664 this_sequence A066666 A066667 A066668
Sequence in context: A117521 A033038 A134917 this_sequence A043325 A023692 A118360
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KEYWORD
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nonn
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AUTHOR
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Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jan 07 2002
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