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A015486
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a(0)=1, a(1)=2, a(n) = sum_{k=0}^{k=n-1} 2^k a(k).
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1
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1, 2, 5, 25, 225, 3825, 126225, 8204625, 1058396625, 272007932625, 139540069436625, 143028571172540625, 293065542332535740625, 1200689526936398929340625, 9837249294189916428087740625, 161183329685301780674217630140625
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OFFSET
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0,2
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LINKS
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PROG
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(Magma) I:=[1, 2, 5]; [n le 3 select I[n] else (2^(n-2)+1)*Self(n-1): n in [1..18]]; // Vincenzo Librandi, Nov 10 2012
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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