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Search: id:A082023
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| A082023 |
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Number of partitions of n into 2 parts which are not relatively prime. |
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+0
2
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| 0, 0, 0, 0, 1, 0, 2, 0, 2, 1, 3, 0, 4, 0, 4, 3, 4, 0, 6, 0, 6, 4, 6, 0, 8, 2, 7, 4, 8, 0, 11, 0, 8, 6, 9, 5, 12, 0, 10, 7, 12, 0, 15, 0, 12, 10, 12, 0, 16, 3, 15, 9, 14, 0, 18, 7, 16, 10, 15, 0, 22, 0, 16, 13, 16, 8, 23, 0, 18, 12, 23, 0, 24, 0, 19, 17, 20, 8, 27, 0, 24, 13, 21, 0, 30, 10, 22
(list; graph; listen)
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OFFSET
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0,7
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COMMENT
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a(p) = 0 if p is prime.
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FORMULA
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a(n) = floor((n-phi(n)/2), where phi(n)=A000010(n) is Euler's totient function. - Dean Hickerson (dean(AT)math.ucdavis.edu), Apr 22 2003
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EXAMPLE
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a(14) = 4 and the partitions are (12,2), (10,4), (8,6) and (7,7).
a(13) = 0 as for all r + s = 13, r > 0, s > 0, gcd(r,s) = 1.
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CROSSREFS
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Cf. A082024.
Adjacent sequences: A082020 A082021 A082022 this_sequence A082024 A082025 A082026
Sequence in context: A127185 A055136 A074397 this_sequence A078152 A028932 A076473
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Apr 07 2003
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EXTENSIONS
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More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 20 2003
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