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Table of n, a(n) for n=1..26.
Select[Range[0, 2000], PrimeQ[4*7^#+1]&]
Sequence in context: A014689 A117206 A026443 * A278965 A032858 A181498
Adjacent sequences: A204320 A204321 A204322 * A204324 A204325 A204326
José María Grau Ribas, Jan 14 2012
a(17)-a(26) from Predrag Kurtovic, May 24 2015