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A006485
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a(n) = (2^(2^n + 1) + 1)/3.
(Formerly M2912)
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2
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3, 11, 171, 43691, 2863311531, 12297829382473034411, 226854911280625642308916404954512140971, 77194726158210796949047323339125271902179989777093709359638389338608753093291
(list;
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refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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FORMULA
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MATHEMATICA
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PROG
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(PARI) {a(n) = if(n > 0, (2^(2^n + 1) + 1)/3, 0)}; /* Michael Somos, Mar 30 2020 */
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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Dennis S. Kluk (mathemagician(AT)ameritech.net)
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STATUS
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approved
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