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A060824
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4-wave sequence beginning with 2s.
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0
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2, 2, 2, 2, 4, 6, 8, 14, 18, 20, 38, 52, 60, 112, 150, 170, 320, 432, 492, 924, 1244, 1414, 2658, 3582, 4074, 7656, 10314, 11728, 22042, 29698, 33772, 63470, 85512, 97240, 182752, 246222, 279994, 526216, 708968, 806208, 1515176, 2041392, 2321386
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OFFSET
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2,1
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COMMENTS
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Primes are the numbers >=2 which have no nontrivial divisor: a(p)=0.
Also: a(n)= A032741(n)-1, n>=2 (from number of divisors <n, called proper divisors).
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LINKS
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Index entries for linear recurrences with constant coefficients, signature (1, -1, 3, -3, 3, 0, 0, 0, -1, 1, -1).
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FORMULA
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a(n)=2*a(n-3)+3*a(n-6)-a(n-9)-a(n-12) - Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), Jan 12 2003
G.f.: -2*x^2*(x^5-2*x^4+2*x^3-x^2-1)/((x^2-x+1)*(x^9-3*x^3+1)). - Colin Barker, Nov 09 2012
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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