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Search: id:A122961
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| A122961 |
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Alternately form product and sum of all previous terms. |
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+0
1
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| 1, 1, 1, 3, 3, 9, 81, 99, 649539, 649737, 274124633198656977, 274124633199956451, 20598907656583661830059012023854018733151994905840579, 20598907656583661830059012023854019281401261305753481
(list; graph; listen)
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OFFSET
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1,4
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COMMENT
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Note that definition does not make a(1) a special case; it is the empty product, which is 1. If we started with addition, the sequence would be all zeros.
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FORMULA
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a(1) = a(2) = 1. For n > 1, a(2n-1) = a(2n-3)^2 * a(2n-2), a(2n) = 2 * a(2n-2) + a(2n-1).
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CROSSREFS
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Cf. A039941, A000004.
Sequence in context: A100239 A038080 A115564 this_sequence A165421 A100731 A072004
Adjacent sequences: A122958 A122959 A122960 this_sequence A122962 A122963 A122964
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KEYWORD
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nonn
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AUTHOR
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Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net), Oct 26 2006
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