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 A104479 Positive integers n such that n^16 + 1 is semiprime (A001358). 13
 3, 4, 9, 12, 14, 16, 18, 20, 26, 29, 40, 41, 48, 58, 70, 73, 81, 87, 92, 96, 104, 111, 113, 114, 118, 122, 130, 140, 142, 144, 146, 150, 157, 162, 164, 167, 168, 172, 173, 184, 187, 192, 194, 195, 199, 200, 202, 208, 220, 230, 232, 244, 253, 256, 266, 278, 292, 295, 298 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS n^16 + 1 is an irreducible polynomial over Z and thus can be either prime (A006313) or semiprime. LINKS Robert Price, Table of n, a(n) for n = 1..102 FORMULA a(n)^16 + 1 is semiprime (A001358). EXAMPLE 3^16 + 1 = 43046722 = 2 * 21523361, 4^16 + 1 = 4294967297 = 641 * 6 700417, 9^16 + 1 = 1853020188851842 = 2 * 926510094425921, 12^16 + 1 = 184884258895036417 = 153953 * 1200913648289, 200^16 + 1 = 6553600000000000000000000000000000001 = 162123499503471553 * 40423504427621041217. MATHEMATICA Select[Range[300], PrimeOmega[#^16+1]==2&] (* Harvey P. Dale, Aug 21 2011 *) Select[Range[1000], 2 == Total[Transpose[FactorInteger[#^16 + 1]][[2]]] &] (* Robert Price, Mar 11 2015 *) PROG (MAGMA) IsSemiprime:=func< n | &+[ k[2]: k in Factorization(n) ] eq 2 >; [n: n in [2..300]|IsSemiprime(n^16+1)] // Vincenzo Librandi, Dec 21 2010 CROSSREFS Cf. A006313, A001358, A085722, A096173, A186669, A104238, A103854, A105041, A105066, A105078, A105122, A105142, A105237, A104335, A104479, A104494, A104657, A105282. Sequence in context: A287400 A309758 A047075 * A067163 A287450 A010394 Adjacent sequences:  A104476 A104477 A104478 * A104480 A104481 A104482 KEYWORD easy,nonn AUTHOR Jonathan Vos Post, Apr 18 2005 EXTENSIONS More terms from Vincenzo Librandi, Dec 21 2010 Corrected (adding 202, 208, and 220) by Harvey P. Dale, Aug 21 2011 STATUS approved

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Last modified April 14 12:11 EDT 2021. Contains 342949 sequences. (Running on oeis4.)