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Search: id:A091703
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| A091703 |
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Count, setting 5n to zero. |
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+0
1
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| 0, 1, 2, 3, 4, 0, 6, 7, 8, 9, 0, 11, 12, 13, 14, 0, 16, 17, 18, 19, 0, 21, 22, 23, 24, 0, 26, 27, 28, 29, 0, 31, 32, 33, 34, 0, 36, 37, 38, 39, 0, 41, 42, 43, 44, 0, 46, 47, 48, 49, 0, 51, 52, 53, 54, 0, 56, 57, 58, 59, 0, 61, 62, 63, 64, 0, 66, 67, 68, 69, 0, 71, 72, 73, 74, 0, 76, 77
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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Multiplicative with a(5^e) = 0, a(p^e) = p^e otherwise. Mitch Harris (Harris.Mitchell(AT)mgh.harvard.edu) Jun 09, 2005.
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FORMULA
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a(n)=product{k=0..4, sum{j=1..n, e^(2pi*Ijk/5}}, I=sqrt(-1); a(n)=cos(4pi*n/5+2pi/5)(ncos(2pi*n/5+pi/5)/5+nsqrt(1/5-2sqrt(5)/25)sin(2pi*n/5+pi/5)+n(1/5- sqrt(5)/5))+sin(4pi*n/5+2pi/5)(nsqrt(2sqrt(5)/25+1/5)cos(2pi*n/5+pi/5)+sqrt(5)nsin(2pi*n/5+ pi/5)/5-nsqrt(2sqrt(5)/25+2/5))-n(sqrt(5)/5+1/5)cos(2pi*n/5+pi/5)-nsqrt(2/5-2sqrt(5)/25)sin(2pi*n/5+pi/5)+4n/5
a(n)=n^5 mod 5n; - Paul Barry (pbarry(AT)wit.ie), Apr 13 2005
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CROSSREFS
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Cf. A091684.
Sequence in context: A119974 A065332 A129468 this_sequence A004180 A011418 A054425
Adjacent sequences: A091700 A091701 A091702 this_sequence A091704 A091705 A091706
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KEYWORD
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easy,nonn,mult
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Jan 30 2004
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