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A072328
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a(n+1)=2*a(n-2)+a(n-1) a(n)=x^n+y^n+z^n.
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0
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3, 0, 2, 6, 2, 10, 14, 14, 34, 42, 62, 110, 146, 234, 366, 526, 834, 1258, 1886, 2926, 4402, 6698, 10254, 15502, 23650, 36010, 54654, 83310, 126674, 192618, 293294, 445966, 678530, 1032554, 1570462, 2389614, 3635570, 5530538, 8414798
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| With the term indexed as shown, has property that p prime => p divides a(p).
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FORMULA
| e=-1/2+i*sqrt(3)/2, e^2=-1/2-i*sqrt(3)/2 x=(1+sqrt(26/27))^(1/3)+(1-sqrt(26/27))^(1/3) y=e*(1+sqrt(26/27))^(1/3)+(e^2)*(1-sqrt(26/27))^(1/3) z=(e^2)*(1+sqrt(26/27))^(1/3)+e*(1-sqrt(26/27))^(1/3) a(n)=x^n+y^n+z^n
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EXAMPLE
| a(10)=2*a(7)+a(8): 62=2*14+34
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CROSSREFS
| Cf. A001608.
Sequence in context: A159959 A058544 A112156 * A135040 A048733 A011075
Adjacent sequences: A072325 A072326 A072327 * A072329 A072330 A072331
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KEYWORD
| easy,nonn
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AUTHOR
| M. Kristof (kristmikl(AT)freemail.hu), Jul 15 2002
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