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A137810
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a(n)=2^(2^n+n)-1.
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0
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1, 7, 63, 2047, 1048575, 137438953471, 1180591620717411303423, 43556142965880123323311949751266331066367, 29642774844752946028434172162224104410437116074403984394101141506025761187823615
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| 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
| Wilfrid Keller, New Cullen Primes, Mathematics of Computation, Vol. 64, No. 212 (Ocober 1995), pp. 1733-1741.
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FORMULA
| a(n) = 2^(2^n+n)-1 = A000225(2^n+n) = A003261(2^n)
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EXAMPLE
| 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
| 2^(2^#+#)-1 &/@Range[0, 8]
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CROSSREFS
| Cf. A000225, A003261, A006127.
Sequence in context: A184141 A152797 A126883 * A036287 A116231 A195630
Adjacent sequences: A137807 A137808 A137809 * A137811 A137812 A137813
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KEYWORD
| easy,nonn
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AUTHOR
| Ant King (mathstutoring(AT)ntlworld.com), Feb 12 2008
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