\"\"

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The explicit formula is \"\".

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Substitute \"\" in \"\".

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\"\"

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\"\".

\

Substitute \"\" in \"\".

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\"\".

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\"\"

\

\"\".

\

Substitute \"\" in \"\".

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\"\".

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\"\"

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\"\".

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Substitute \"\" in \"\".

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\"\".

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\"\"

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\"\"

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\"\".

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The  first four terms are \"\" and \"\".

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\"\"

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The  first four terms are  \"\" and \"\".