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Search: id:A089385
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| A089385 |
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G.f.: Product_{k>=1} Sum_{n>=0} b(n)*x^(kn), where b(n)=-1 if n is congruent to 2, 3, 4, or 5 modulo 8, b(n)=+1 otherwise. |
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+0
1
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| 1, 1, 0, 1, -1, -1, 1, -1, 0, 0, 0, 0, -1, -1, -1, 0, 1, 1, -1, 0, -1, 0, 0, -1, 1, 0, 0, 0, 0, -1, 0, 0, 1, 1, 0, 1, -1, -1, 1, -1, 0, 1, 0, 1, -1, 0, 0, 0, 1, 1, 0, 1, -1, -1, 1, 0, 1, 0, 0, 0, -1, -1, 0, -1, 2, 2, 0, 1, -1, -1, 0, -1, 1, 1, 0, 0, -1, -1, 0, 0, 2, 1, -1, 1, -2, -1, 0, -1, 1, 1, -1, 1, -1, -1, 0, -1, 2, 2, 0, 1, -2, -2, 1, -2, 1, 1, 0, 1, -2
(list; graph; listen)
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OFFSET
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0,65
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COMMENT
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The coefficients of x^k are +1, -1, or zero for k<71.
A089385 and A000041 have the same parity. - Vladeta Jovovic (vladeta(AT)eunet.rs), Dec 31 2003
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FORMULA
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G.f.: Product_{k>0} (1-x^k)*(1+x^k)^2/(1+x^(4*k)). - Vladeta Jovovic (vladeta(AT)eunet.rs), Dec 31 2003
Euler transform of period 8 sequence [1, -1, 1, -2, 1, -1, 1, -1, ...]. - Vladeta Jovovic (vladeta(AT)eunet.rs), Aug 20 2004
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EXAMPLE
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1+x+x^3-x^4-x^5+x^6-x^7-x^12-...
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CROSSREFS
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Cf. A040051.
Sequence in context: A110568 A088689 A076898 this_sequence A124407 A137581 A156311
Adjacent sequences: A089382 A089383 A089384 this_sequence A089386 A089387 A089388
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KEYWORD
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sign,easy
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AUTHOR
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David Newman (davidsnewman(AT)hotmail.com), Dec 28 2003
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EXTENSIONS
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More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Dec 31 2003
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