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Search: id:A137810
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| 1, 7, 63, 2047, 1048575, 137438953471, 1180591620717411303423, 43556142965880123323311949751266331066367, 29642774844752946028434172162224104410437116074403984394101141506025761187823615
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OFFSET
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0,2
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COMMENT
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An integer is simultaneously a Mersenne number and a Woodall number if and only if it is a member of this sequence. Hence this sequence is the intersection of A000225 and A003261.
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REFERENCES
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Keller, Wilfred; New Cullen Primes, Mathematics of Computation, Vol. 64, No. 212. (Ocober 1995), pp. 1733-1741.
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FORMULA
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a(n) = 2^(2^n+n)-1 = A000225(2^n+n) = A003261(2^n)
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EXAMPLE
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The fourth integer which is both a Mersenne number and a Woodall number is 2047. Hence a(3)=2047 (as the offset is zero).
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MATHEMATICA
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2^(2^#+#)-1 &/@Range[0, 8]
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CROSSREFS
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Cf. A000225, A003261, A006127.
Sequence in context: A084063 A152797 A126883 this_sequence A036287 A116231 A136955
Adjacent sequences: A137807 A137808 A137809 this_sequence A137811 A137812 A137813
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KEYWORD
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easy,nonn
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AUTHOR
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Ant King (mathstutoring(AT)ntlworld.com), Feb 12 2008
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