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A291293
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Sequence mod 5 defined by Baldini-Eschgfäller coupled dynamical system (f,lambda,alpha) with f(k) = A000203(k)-1, lambda(y) = 3y+2 mod 5 for y in Y = {0,1,2,3,4}, and alpha(k) = k mod 5 for k in Omega = {primes}.
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2
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2, 3, 2, 0, 0, 2, 0, 0, 3, 1, 1, 3, 1, 1, 2, 2, 4, 4, 0, 0, 1, 3, 4, 2, 0, 3, 2, 4, 0, 1, 3, 3, 1, 3, 0, 2, 4, 2, 4, 1, 2, 3, 1, 3, 0, 2, 1, 2, 1, 0, 3, 3, 0, 0, 0, 4, 4, 4, 3, 1, 2, 1, 2, 1, 1, 2, 3, 2, 1, 1, 0, 3, 1, 1, 4, 2, 3, 4, 1, 4, 3, 3, 1, 3, 0
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OFFSET
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2,1
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COMMENTS
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This sequence assumes that the Erdos conjecture is true, that iterating k -> sigma(k)-1 always reaches a prime (cf. A039654).
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LINKS
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FORMULA
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Let f(k) = A000203(k)-1 = sigma(k) - 1, lambda(y) = 3y+2 mod 5 for y in Y = {0,1,2,3,4}, and alpha(k) = k mod 5 for k in Omega = {primes}. Here sigma is the sum of divisors function A000203.
Then a(n) for n >= 2 is defined by a(n) = alpha(n) if n in Omega, and otherwise by a(n) = lambda(a(f(n))).
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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