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 A099478 Least a(n) such that a(n)*2^n*(2^n-1)-1 is prime. 0
 2, 1, 3, 1, 1, 4, 3, 6, 1, 1, 4, 2, 9, 4, 9, 14, 4, 1, 3, 4, 36, 5, 25, 4, 10, 4, 18, 3, 21, 9, 9, 21, 16, 65, 12, 8, 51, 1, 22, 2, 30, 6, 10, 63, 1, 30, 15, 3, 10, 1, 22, 57, 202, 4, 3, 53, 1, 34, 12, 10, 22, 29, 28, 31, 7, 6, 70, 29, 16, 94, 37, 51, 30, 56, 19, 23, 70, 50, 99, 16, 34, 5 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS EXAMPLE 1*2^6*(2^6-1)-1=4031=29*139 2*2^6*(2^6-1)-1=8063=11*733 3*2^6*(2^6-1)-1=12095=5*2419 4*2^6*(2^6-1)-1=16127 prime so a(6)=4 CROSSREFS Sequence in context: A115139 A198788 A112543 * A133913 A209485 A209344 Adjacent sequences:  A099475 A099476 A099477 * A099479 A099480 A099481 KEYWORD easy,nonn AUTHOR Pierre CAMI, Nov 18 2004 STATUS approved

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Last modified October 23 03:21 EDT 2019. Contains 328335 sequences. (Running on oeis4.)