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A114950
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A quartic quadratic recurrence.
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0
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OFFSET
| 0,3
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COMMENTS
| a(6) has 315 digits. This sequence is related to: A112969 "quartic Fibonacci sequence" a(1) = a(2) = 1; for n>2: a(n) = a(n-1)^4 + a(n-2)^4, which is the quartic (or biquadratic) analogue of the Fibonacci sequence similarly to A000283 being the quadratic analogue of the Fibonacci sequence. Primes in this sequence include a(n) for n = 2, 3. Semiprimes in this sequence include a(n) for n = 5.
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LINKS
| Index entries for sequences of form a(n+1)=a(n)^2 + ...
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FORMULA
| a(0) = a(1) = 1, for n>1 a(n) = a(n-2)^4 + a(n-1)^2.
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EXAMPLE
| a(2) = a(1)^4 + a(0)^2 = 1^4 + 1^2 = 2.
a(3) = a(2)^4 + a(1)^2 = 2^4 + 1^2 = 17.
a(4) = a(3)^4 + a(2)^2 = 17^4 + 2^2 = 83525.
a(5) = a(4)^4 + a(3)^2 = 83525^4 + 17^2 = 48670514501156640914.
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CROSSREFS
| Cf. A000283, A112969, A114793.
Sequence in context: A195003 A071067 A060069 * A170995 A003840 A122540
Adjacent sequences: A114947 A114948 A114949 * A114951 A114952 A114953
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KEYWORD
| easy,nonn
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AUTHOR
| Jonathan Vos Post (jvospost3(AT)gmail.com), Feb 21 2006
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